From 141ebddde0095580dd40039e61075b274d95369c Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Mon, 15 Apr 2024 09:34:23 -0500
Subject: [PATCH 1/8] Continued interpolation cleanup, fixed up setup.py, added
 cli entry point

---
 glhe/profiles/external_base.py                |  7 +-
 glhe/properties/fluid_properties.py           | 27 ++++----
 {standalone => glhe/standalone}/__init__.py   |  0
 {standalone => glhe/standalone}/plant_loop.py |  6 +-
 .../single_u_tube_grouted_borehole.py         | 31 ++++-----
 .../topology/single_u_tube_grouted_segment.py | 68 +++++++++++--------
 .../single_u_tube_pass_through_segment.py     |  5 +-
 glhe/utilities/functions.py                   |  2 +-
 requirements.txt                              | 19 ++++--
 setup.py                                      | 16 ++++-
 .../test_single_u_tube_grouted_segment.py     | 11 ++-
 unit_tests/standalone/test_plant_loop.py      |  2 +-
 12 files changed, 115 insertions(+), 79 deletions(-)
 rename {standalone => glhe/standalone}/__init__.py (100%)
 rename {standalone => glhe/standalone}/plant_loop.py (99%)

diff --git a/glhe/profiles/external_base.py b/glhe/profiles/external_base.py
index 195d7409..26a04494 100644
--- a/glhe/profiles/external_base.py
+++ b/glhe/profiles/external_base.py
@@ -1,5 +1,6 @@
 import pandas as pd
-from scipy.interpolate import interp1d
+
+from glhe.utilities.functions import Interpolator1D
 
 
 class ExternalBase(object):
@@ -18,7 +19,7 @@ def __init__(self, path, col_num):
         y_range.append(y_range[0])
         self.max_time = x_range[-1]
 
-        self._interp_values = interp1d(x_range, y_range)
+        self._interp_values = Interpolator1D(x_range, y_range)
 
     def get_value(self, time) -> float:
-        return float(self._interp_values(time % self.max_time))
+        return float(self._interp_values.interpolate(time % self.max_time))
diff --git a/glhe/properties/fluid_properties.py b/glhe/properties/fluid_properties.py
index 3222ffa9..dadcf92e 100644
--- a/glhe/properties/fluid_properties.py
+++ b/glhe/properties/fluid_properties.py
@@ -1,10 +1,9 @@
 from CoolProp.CoolProp import PropsSI
 from numpy import arange
-from scipy.interpolate import interp1d
 
 from glhe.properties.fluid_property_types import FluidPropertyType
 from glhe.properties.fluid_types import FluidType
-from glhe.utilities.functions import c_to_k, k_to_c
+from glhe.utilities.functions import c_to_k, k_to_c, Interpolator1D
 
 
 class Fluid:
@@ -39,12 +38,12 @@ def __init__(self, inputs: dict):
         rho_vals = [self.calc_density(x) for x in temps]
         rho_cp_vals = [self.calc_vol_heat_capacity(x) for x in temps]
 
-        self.cp_interp = interp1d(temps, cp_vals)
-        self.k_interp = interp1d(temps, k_vals)
-        self.mu_interp = interp1d(temps, mu_vals)
-        self.pr_interp = interp1d(temps, pr_vals)
-        self.rho_interp = interp1d(temps, rho_vals)
-        self.rho_cp_interp = interp1d(temps, rho_cp_vals)
+        self.cp_interp = Interpolator1D(temps, cp_vals)
+        self.k_interp = Interpolator1D(temps, k_vals)
+        self.mu_interp = Interpolator1D(temps, mu_vals)
+        self.pr_interp = Interpolator1D(temps, pr_vals)
+        self.rho_interp = Interpolator1D(temps, rho_vals)
+        self.rho_cp_interp = Interpolator1D(temps, rho_cp_vals)
 
     @staticmethod
     def get_fluid_str(fluid_enum, concentration: int | float) -> str:
@@ -99,7 +98,7 @@ def get_cp(self, temperature: int | float) -> float:
         :returns fluid specific heat in [J/kg-K]
         """
 
-        return float(self.cp_interp(temperature))
+        return self.cp_interp.interpolate(temperature)
 
     def get_k(self, temperature: int | float) -> float:
         """
@@ -109,7 +108,7 @@ def get_k(self, temperature: int | float) -> float:
         :return: fluid conductivity in [W/m-K]
         """
 
-        return float(self.k_interp(temperature))
+        return self.k_interp.interpolate(temperature)
 
     def get_mu(self, temperature: int | float) -> float:
         """
@@ -119,7 +118,7 @@ def get_mu(self, temperature: int | float) -> float:
         :return: fluid viscosity in [Pa-s]
         """
 
-        return float(self.mu_interp(temperature))
+        return self.mu_interp.interpolate(temperature)
 
     def get_pr(self, temperature: int | float) -> float:
         """
@@ -129,7 +128,7 @@ def get_pr(self, temperature: int | float) -> float:
         :return: fluid Prandtl number
         """
 
-        return float(self.pr_interp(temperature))
+        return self.pr_interp.interpolate(temperature)
 
     def get_rho(self, temperature: int | float) -> float:
         """
@@ -139,7 +138,7 @@ def get_rho(self, temperature: int | float) -> float:
         :return: fluid density in [kg/m^3]
         """
 
-        return float(self.rho_interp(temperature))
+        return self.rho_interp.interpolate(temperature)
 
     def get_rho_cp(self, temperature: int | float) -> float:
         """
@@ -149,7 +148,7 @@ def get_rho_cp(self, temperature: int | float) -> float:
         :return: fluid volume-specific heat capacity in [J/m3-K]
         """
 
-        return float(self.rho_cp_interp(temperature))
+        return self.rho_cp_interp.interpolate(temperature)
 
     def calc_conductivity(self, temperature: int | float) -> float:
         """
diff --git a/standalone/__init__.py b/glhe/standalone/__init__.py
similarity index 100%
rename from standalone/__init__.py
rename to glhe/standalone/__init__.py
diff --git a/standalone/plant_loop.py b/glhe/standalone/plant_loop.py
similarity index 99%
rename from standalone/plant_loop.py
rename to glhe/standalone/plant_loop.py
index 842d4140..715ffa47 100644
--- a/standalone/plant_loop.py
+++ b/glhe/standalone/plant_loop.py
@@ -148,5 +148,9 @@ def collect_outputs(self, sim_time):
         self.op.collect_output(d)
 
 
-if __name__ == "__main__":
+def main():
     PlantLoop(sys.argv[1]).simulate()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/glhe/topology/single_u_tube_grouted_borehole.py b/glhe/topology/single_u_tube_grouted_borehole.py
index cd628185..57719cfe 100644
--- a/glhe/topology/single_u_tube_grouted_borehole.py
+++ b/glhe/topology/single_u_tube_grouted_borehole.py
@@ -6,7 +6,7 @@
 from glhe.output_processor.report_types import ReportTypes
 from glhe.properties.base_properties import PropertiesBase
 from glhe.topology.pipe import Pipe
-from glhe.topology.single_u_tube_grouted_segment import SingleUTubeGroutedSegment
+from glhe.topology.single_u_tube_grouted_segment import SingleUTubeGroutedSegment, TimeStepStructure
 from glhe.topology.single_u_tube_pass_through_segment import SingleUTubePassThroughSegment
 from glhe.utilities.functions import merge_dicts
 
@@ -313,10 +313,7 @@ def simulate_time_step(self, inputs: SimulationResponse) -> SimulationResponse:
 
         r_12, r_b = self.calc_direct_coupling_resistance(inlet_temp, flow_rate=flow_rate)
 
-        seg_inputs = {'boundary-temperature': bh_wall_temp,
-                      'rb': r_b,
-                      'flow-rate': flow_rate,
-                      'dc-resist': r_12}
+        seg_inputs = TimeStepStructure(boundary_temp=bh_wall_temp, bh_resist=r_b, flow_rate=flow_rate, dc_resist=r_12)
 
         self.pipe_1.simulate_time_step(SimulationResponse(time, time_step, flow_rate, inlet_temp))
 
@@ -325,13 +322,13 @@ def simulate_time_step(self, inputs: SimulationResponse) -> SimulationResponse:
             for idx, seg in enumerate(self.segments):
 
                 if idx == 0:
-                    seg_inputs['inlet-1-temp'] = self.pipe_1.outlet_temperature
-                    seg_inputs['inlet-2-temp'] = self.segments[idx + 1].get_outlet_2_temp()
+                    seg_inputs.inlet_temp_1 = self.pipe_1.outlet_temperature
+                    seg_inputs.inlet_temp_2 = self.segments[idx + 1].get_outlet_2_temp()
                 elif idx == self.num_segments:
-                    seg_inputs['inlet-1-temp'] = self.segments[idx - 1].get_outlet_1_temp()
+                    seg_inputs.inlet_temp_1 = self.segments[idx - 1].get_outlet_1_temp()
                 else:
-                    seg_inputs['inlet-1-temp'] = self.segments[idx - 1].get_outlet_1_temp()
-                    seg_inputs['inlet-2-temp'] = self.segments[idx + 1].get_outlet_2_temp()
+                    seg_inputs.inlet_temp_1 = self.segments[idx - 1].get_outlet_1_temp()
+                    seg_inputs.inlet_temp_2 = self.segments[idx + 1].get_outlet_2_temp()
 
                 seg.simulate_time_step(time_step, seg_inputs)
 
@@ -363,12 +360,12 @@ def report_outputs(self) -> dict:
 
         d = merge_dicts(d, self.pipe_1.report_outputs())
 
-        d_self = {'{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.HeatRate): self.heat_rate,
-                  '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.HeatRateBH): self.heat_rate_bh,
-                  '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.InletTemp): self.inlet_temperature,
-                  '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.OutletTemp): self.outlet_temperature,
-                  '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.BHResist): self.resist_bh_ave,
-                  '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.BHIntResist): self.resist_bh_total_internal,
-                  '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.BHDCResist): self.resist_bh_direct_coupling}
+        d_self = {f"{self.Type}:{self.name}:{ReportTypes.HeatRate}": self.heat_rate,
+                  f"{self.Type}:{self.name}:{ReportTypes.HeatRateBH}": self.heat_rate_bh,
+                  f"{self.Type}:{self.name}:{ReportTypes.InletTemp}": self.inlet_temperature,
+                  f"{self.Type}:{self.name}:{ReportTypes.OutletTemp}": self.outlet_temperature,
+                  f"{self.Type}:{self.name}:{ReportTypes.BHResist}": self.resist_bh_ave,
+                  f"{self.Type}:{self.name}:{ReportTypes.BHIntResist}": self.resist_bh_total_internal,
+                  f"{self.Type}:{self.name}:{ReportTypes.BHDCResist}": self.resist_bh_direct_coupling}
 
         return merge_dicts(d, d_self)
diff --git a/glhe/topology/single_u_tube_grouted_segment.py b/glhe/topology/single_u_tube_grouted_segment.py
index 77557991..497497e3 100644
--- a/glhe/topology/single_u_tube_grouted_segment.py
+++ b/glhe/topology/single_u_tube_grouted_segment.py
@@ -1,7 +1,8 @@
+from dataclasses import dataclass
 from math import pi
 
 import numpy as np
-from scipy.integrate import solve_ivp
+from scipy.integrate import RK45
 
 from glhe.input_processor.component_types import ComponentTypes
 from glhe.output_processor.report_types import ReportTypes
@@ -9,21 +10,26 @@
 from glhe.topology.pipe import Pipe
 
 
-class SingleUTubeGroutedSegment(object):
+@dataclass
+class TimeStepStructure:
+    flow_rate: float = 0.0
+    inlet_temp_1: float = 0.0
+    inlet_temp_2: float = 0.0
+    boundary_temp: float = 0.0
+    bh_resist: float = 0.0
+    dc_resist: float = 0.0
+
+
+class SingleUTubeGroutedSegment:
     Type = ComponentTypes.SegmentSingleUTubeGrouted
 
     def __init__(self, inputs, ip, op):
         self.name = inputs['segment-name']
-        self.ip = ip
-        self.op = op
-
         self.fluid = ip.props_mgr.fluid
         self.soil = ip.props_mgr.soil
 
         if 'average-pipe' in inputs:
-
-            pipe_inputs = {'average-pipe': inputs['average-pipe'],
-                           'length': inputs['length']}
+            pipe_inputs = {'average-pipe': inputs['average-pipe'], 'length': inputs['length']}
         else:
             pipe_inputs = {'pipe-def-name': inputs['pipe-def-name'], 'length': inputs['length']}
 
@@ -79,8 +85,7 @@ def calc_seg_volume(self):
         return pi / 4 * self.diameter ** 2 * self.length
 
     def right_hand_side(self, _, y):
-        num_equations = self.num_equations
-        r = np.zeros(num_equations)
+        r = np.zeros(self.num_equations)
 
         dz = self.length
         t_b = self.boundary_temp
@@ -135,18 +140,27 @@ def get_outlet_1_temp(self):
     def get_outlet_2_temp(self):
         return self.y[1]
 
-    def simulate_time_step(self, time_step: int, inputs: dict) -> np.ndarray:
-        self.flow_rate = inputs['flow-rate']
-        self.inlet_temp_1 = inputs['inlet-1-temp']
-        self.inlet_temp_2 = inputs['inlet-2-temp']
-        self.boundary_temp = inputs['boundary-temperature']
-        self.bh_resist = inputs['rb']
-        self.dc_resist = inputs['dc-resist']
-        self.fluid_cp = self.fluid.get_cp(inputs['inlet-1-temp'])
-        self.fluid_heat_capacity = self.fluid.get_rho(inputs['inlet-1-temp']) * self.fluid_cp
-
-        ret = solve_ivp(self.right_hand_side, [0, time_step], self.y)
-        self.y = ret.y[:, -1]
+    def simulate_time_step(self, time_step: float, inputs: TimeStepStructure) -> np.ndarray:
+        """
+        Simulate a single time step for this segment.  Solves the equations simultaneously using
+        RK45 method.
+        Parameters
+        :param time_step: float Time step in seconds?
+        :param inputs: TimeStepStructure of data to begin this time step.
+        """
+        self.flow_rate = inputs.flow_rate
+        self.inlet_temp_1 = inputs.inlet_temp_1
+        self.inlet_temp_2 = inputs.inlet_temp_2
+        self.boundary_temp = inputs.boundary_temp
+        self.bh_resist = inputs.bh_resist
+        self.dc_resist = inputs.dc_resist
+        self.fluid_cp = self.fluid.get_cp(self.inlet_temp_1)
+        self.fluid_heat_capacity = self.fluid.get_rho(self.inlet_temp_1) * self.fluid_cp
+
+        solver = RK45(self.right_hand_side, 0, self.y, time_step)
+        while solver.status != 'finished':
+            solver.step()
+        self.y = solver.y
 
         # update report vars
         self.heat_rate_bh = self.get_heat_rate_bh()
@@ -155,8 +169,8 @@ def simulate_time_step(self, time_step: int, inputs: dict) -> np.ndarray:
         return self.y
 
     def report_outputs(self) -> dict:
-        return {'{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.InletTemp_Leg1): self.inlet_temp_1,
-                '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.OutletTemp_Leg1): self.outlet_temp_1,
-                '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.InletTemp_Leg2): self.inlet_temp_2,
-                '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.OutletTemp_Leg2): self.outlet_temp_2,
-                '{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.HeatRateBH): self.heat_rate_bh}
+        return {f"{self.Type}:{self.name}:{ReportTypes.InletTemp_Leg1}": self.inlet_temp_1,
+                f"{self.Type}:{self.name}:{ReportTypes.OutletTemp_Leg1}": self.outlet_temp_1,
+                f"{self.Type}:{self.name}:{ReportTypes.InletTemp_Leg2}": self.inlet_temp_2,
+                f"{self.Type}:{self.name}:{ReportTypes.OutletTemp_Leg2}": self.outlet_temp_2,
+                f"{self.Type}:{self.name}:{ReportTypes.HeatRateBH}": self.heat_rate_bh}
diff --git a/glhe/topology/single_u_tube_pass_through_segment.py b/glhe/topology/single_u_tube_pass_through_segment.py
index fc10ffdc..a06b0954 100644
--- a/glhe/topology/single_u_tube_pass_through_segment.py
+++ b/glhe/topology/single_u_tube_pass_through_segment.py
@@ -1,5 +1,6 @@
 from glhe.input_processor.component_types import ComponentTypes
 from glhe.output_processor.report_types import ReportTypes
+from glhe.topology.single_u_tube_grouted_segment import TimeStepStructure
 
 
 class SingleUTubePassThroughSegment(object):
@@ -16,8 +17,8 @@ def __init__(self, inputs, ip, op):
     def get_outlet_2_temp(self):
         return self.temperature
 
-    def simulate_time_step(self, _, inputs: dict):
-        self.temperature = inputs['inlet-1-temp']
+    def simulate_time_step(self, _, inputs: TimeStepStructure):
+        self.temperature = inputs.inlet_temp_1
 
     def report_outputs(self) -> dict:
         return {'{:s}:{:s}:{:s}'.format(self.Type, self.name, ReportTypes.OutletTemp): self.temperature}
diff --git a/glhe/utilities/functions.py b/glhe/utilities/functions.py
index f48c29a1..d3e9c9d7 100644
--- a/glhe/utilities/functions.py
+++ b/glhe/utilities/functions.py
@@ -482,7 +482,7 @@ def write_arrays_to_csv(path: str, arrays: list | np.ndarray) -> None:
 
 class Interpolator1D:
 
-    def __init__(self, x_data: np.ndarray, y_data: np.ndarray):  # TODO: Try to use pathlib internally everywhere
+    def __init__(self, x_data: np.ndarray, y_data: np.ndarray | list[float]):  # TODO: Use pathlib internally everywhere
         """
         1D Interpolation Class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
 
diff --git a/requirements.txt b/requirements.txt
index e6457273..f7f28901 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,14 +1,23 @@
+# Core library dependencies
 CoolProp
-coverage
-coveralls
 jsonschema
-matplotlib
 numpy
 pandas
 pygfunction
 scipy
+
+# Dependencies needed to build wheels for PyPi
+wheel
+
+# Dependencies for building documentation (for RTD)
 Sphinx
+sphinx-rtd-theme
+
+# Dependencies needed to assist in running linting, unit tests and coverage
 pytest
 flake8
-wheel
-sphinx-rtd-theme
+coverage
+coveralls
+
+# Dependencies needed for running the extra validation studies and such
+matplotlib
diff --git a/setup.py b/setup.py
index 7e4a8438..3cf49f17 100755
--- a/setup.py
+++ b/setup.py
@@ -11,9 +11,23 @@
     version='0.1',
     author="Matt Mitchell",
     author_email="mitchute@gmail.com",
-    packages=['glhe'],
+    packages=[
+        'glhe',
+        'glhe.aggregation',
+        'glhe.g_function',
+        'glhe.ground_temps',
+        'glhe.input_processor',
+        'glhe.interface',
+        'glhe.output_processor',
+        'glhe.profiles',
+        'glhe.properties',
+        'glhe.standalone',
+        'glhe.topology',
+        'glhe.utilities',
+    ],
     license='MIT',
     install_requires=requirements,
     long_description=open('README.md').read(),
     long_description_content_type='text/markdown',
+    entry_points={'console_scripts': ['glhe=glhe.standalone.plant_loop:main',]}
 )
diff --git a/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py b/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py
index 369fb1a3..ce158a32 100644
--- a/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py
+++ b/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py
@@ -4,7 +4,7 @@
 
 from glhe.input_processor.input_processor import InputProcessor
 from glhe.output_processor.output_processor import OutputProcessor
-from glhe.topology.single_u_tube_grouted_segment import SingleUTubeGroutedSegment
+from glhe.topology.single_u_tube_grouted_segment import SingleUTubeGroutedSegment, TimeStepStructure
 from glhe.utilities.functions import write_json
 
 
@@ -62,12 +62,9 @@ def test_volume(self):
 
     def test_simulate_time_step(self):
         tst = self.add_instance()
-        inputs = {'boundary-temperature': 20,
-                  'inlet-1-temp': 30,
-                  'inlet-2-temp': 25,
-                  'flow-rate': 0.2,
-                  'rb': 0.16,
-                  'dc-resist': 2.28}
+        inputs = TimeStepStructure(
+            flow_rate=0.2, inlet_temp_1=30.0, inlet_temp_2=25.0, boundary_temp=20.0, bh_resist=0.16, dc_resist=2.28
+        )
 
         ret_temps = tst.simulate_time_step(1, inputs)
 
diff --git a/unit_tests/standalone/test_plant_loop.py b/unit_tests/standalone/test_plant_loop.py
index 97a73aa4..6b8cad46 100644
--- a/unit_tests/standalone/test_plant_loop.py
+++ b/unit_tests/standalone/test_plant_loop.py
@@ -4,7 +4,7 @@
 
 from glhe.utilities.functions import load_json
 from glhe.utilities.functions import write_json
-from standalone.plant_loop import PlantLoop
+from glhe.standalone.plant_loop import PlantLoop
 
 norm = os.path.normpath
 join = os.path.join

From de819fa3681993f5f9e14b3937cfbe070fa6ed4e Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Mon, 15 Apr 2024 13:57:16 -0500
Subject: [PATCH 2/8] Use Path library all over the place

---
 glhe/aggregation/base_agg.py                  | 24 +++++------
 glhe/aggregation/dynamic.py                   | 28 +++++--------
 glhe/aggregation/no_agg.py                    |  1 +
 glhe/aggregation/static.py                    |  3 +-
 glhe/ground_temps/base.py                     |  4 +-
 glhe/input_processor/input_processor.py       | 10 +++--
 glhe/output_processor/output_processor.py     | 13 +++---
 glhe/profiles/external_base.py                |  6 ++-
 glhe/standalone/plant_loop.py                 | 20 +++++----
 glhe/utilities/functions.py                   | 40 ++++++++++--------
 .../input_processor/test_input_processor.py   | 26 +++++-------
 .../test_plant_loop_component_factory.py      | 24 +++++------
 .../output_processor/test_output_processor.py |  6 +--
 .../glhe/profiles/test_constant_flow.py       |  6 +--
 .../glhe/profiles/test_constant_load.py       |  6 +--
 .../glhe/profiles/test_constant_temp.py       |  6 +--
 .../glhe/profiles/test_external_base.py       |  8 ++--
 .../glhe/profiles/test_external_flow.py       | 41 ++++++++++---------
 .../glhe/profiles/test_external_load.py       | 16 ++++----
 .../glhe/profiles/test_external_temps.py      | 16 +++++---
 unit_tests/glhe/profiles/test_flow_factory.py | 22 +++++-----
 unit_tests/glhe/profiles/test_load_factory.py | 19 +++++----
 unit_tests/glhe/profiles/test_pulse_load.py   |  6 +--
 .../glhe/profiles/test_sinusoid_load.py       |  6 +--
 .../glhe/profiles/test_synthetic_load.py      |  6 +--
 .../glhe/properties/test_fluid_types.py       | 16 ++++----
 .../topology/test_ground_heat_exhanger.py     | 12 +++---
 ...st_ground_heat_exhanger_short_time_step.py | 14 ++++---
 unit_tests/glhe/topology/test_path.py         | 11 ++---
 unit_tests/glhe/topology/test_pipe.py         |  6 +--
 .../test_single_u_tube_grouted_borehole.py    |  6 +--
 .../test_single_u_tube_grouted_segment.py     |  6 +--
 .../glhe/topology/test_swedish_heat_pump.py   | 12 +++---
 unit_tests/glhe/utilities/test_functions.py   | 35 ++++++++--------
 unit_tests/standalone/test_plant_loop.py      | 23 +++++------
 35 files changed, 255 insertions(+), 249 deletions(-)

diff --git a/glhe/aggregation/base_agg.py b/glhe/aggregation/base_agg.py
index 43ecef7a..36d734b3 100644
--- a/glhe/aggregation/base_agg.py
+++ b/glhe/aggregation/base_agg.py
@@ -1,14 +1,9 @@
-import os
 from abc import ABC, abstractmethod
+from pathlib import Path
 
 import numpy as np
 
-from glhe.utilities.functions import Interpolator1D, Interpolator1DFromFile
-from glhe.utilities.functions import Interpolator2DFromFile
-
-join = os.path.join
-norm = os.path.normpath
-cwd = os.getcwd()
+from glhe.utilities.functions import InterpolatorBase, Interpolator1D, Interpolator1DFromFile, Interpolator2DFromFile
 
 
 class BaseAgg(ABC):
@@ -16,21 +11,26 @@ class BaseAgg(ABC):
     def __init__(self, inputs: dict):
         # g-function values
         if 'g-function-path' in inputs:
-            path_g = norm(join(cwd, inputs['g-function-path']))
-            self.interp_g = Interpolator1DFromFile(path_g)
+            p = Path(inputs['g-function-path'])
+            if not p.is_absolute():
+                p = Path.cwd() / inputs['g-function-path']
+            self.interp_g = Interpolator1DFromFile(p)
         elif 'lntts' and 'g-values' in inputs:
             data_g = np.transpose(np.array([inputs['lntts'], inputs['g-values']]))
-            self.interp_g = Interpolator1D(data_g[:, 0], data_g[:, 1])
+            self.interp_g: InterpolatorBase = Interpolator1D(data_g[:, 0], data_g[:, 1])
         else:
             raise KeyError('g-function data not found.')
 
         # g_b-function values
         self.interp_g_b = None
         if 'g_b-function-path' in inputs:
+            p = Path(inputs['g_b-function-path'])
+            if not p.is_absolute():
+                p = Path.cwd() / inputs['g_b-function-path']
             if 'g_b-flow-rates' in inputs:
-                self.interp_g_b = Interpolator2DFromFile(inputs['g_b-function-path'], inputs['g_b-flow-rates'])
+                self.interp_g_b: InterpolatorBase = Interpolator2DFromFile(p, inputs['g_b-flow-rates'])
             else:
-                self.interp_g_b = Interpolator1DFromFile(inputs['g_b-function-path'])
+                self.interp_g_b: InterpolatorBase = Interpolator1DFromFile(p)
         elif 'lntts_b' and 'g_b-values' in inputs:
             data_g_b = np.transpose(np.array([inputs['lntts_b'], inputs['g_b-values']]))
             self.interp_g_b = Interpolator1D(data_g_b[:, 0], data_g_b[:, 1])
diff --git a/glhe/aggregation/dynamic.py b/glhe/aggregation/dynamic.py
index 5cb0e517..6b9d59aa 100644
--- a/glhe/aggregation/dynamic.py
+++ b/glhe/aggregation/dynamic.py
@@ -23,16 +23,14 @@ def __init__(self, inputs: dict):
         self.sub_hr = SubHour(inputs)
 
         # set expansion rate. apply default if needed.
-        try:
+        self.exp_rate = 1.62
+        if 'expansion-rate' in inputs:
             self.exp_rate = inputs['expansion-rate']
-        except KeyError:  # pragma: no cover
-            self.exp_rate = 1.62  # pragma: no cover
 
         # set the number of bins per level. apply default if needed.
-        try:
+        self.bins_per_level = 9
+        if 'number-bins-per-level' in inputs:
             self.bins_per_level = inputs['number-bins-per-level']
-        except KeyError:  # pragma: no cover
-            self.bins_per_level = 9  # pragma: no cover
 
         # total simulation runtime to make available for method
         run_time = inputs['runtime']
@@ -47,17 +45,13 @@ def __init__(self, inputs: dict):
         t = SEC_IN_HOUR
 
         # initialize the dynamic method
-        initialized = False
-        while not initialized:
+        while True:
             for _ in range(self.bins_per_level):
                 t += dt
                 self.energy = np.insert(self.energy, 0, 0)
                 self.dts = np.insert(self.dts, 0, dt)
-
                 if t >= run_time:
-                    initialized = True
-                    break
-
+                    return
             dt *= self.exp_rate
 
     def aggregate(self, time: int, energy: float):
@@ -111,7 +105,8 @@ def calc_temporal_superposition(self, time_step: int, flow_rate: float = None) -
             if not flow_rate:
                 g_b = self.interp_g_b.interpolate(lntts)
             else:
-                g_b = np.flipud(self.interp_g_b(lntts, flow_rate))
+                # TODO: This is not covered by tests, and may need adjusting the interpolator class to work properly
+                g_b = np.flipud(self.interp_g_b.interpolate(lntts, flow_rate))
             return float(np.dot(dq, g)), float(np.dot(dq, g_b))
         else:
             # convolution for "g" g-functions only
@@ -119,14 +114,11 @@ def calc_temporal_superposition(self, time_step: int, flow_rate: float = None) -
 
     def get_g_value(self, time_step: int) -> float:
         lntts = np.log(time_step / self.ts)
-        return float(self.interp_g.interpolate(lntts))
+        return self.interp_g.interpolate(lntts)
 
     def get_g_b_value(self, time_step: int, flow_rate: float = None) -> float:
         lntts = np.log(time_step / self.ts)
-        if not flow_rate:
-            return float(self.interp_g_b.interpolate(lntts))
-        else:
-            return float(self.interp_g_b.interpolate(lntts, flow_rate))
+        return self.interp_g_b.interpolate(lntts, flow_rate)
 
     def get_q_prev(self) -> float:
         return float(self.sub_hr.energy[-1] / self.sub_hr.dts[-1])
diff --git a/glhe/aggregation/no_agg.py b/glhe/aggregation/no_agg.py
index f8bbf0f9..545fb5a4 100644
--- a/glhe/aggregation/no_agg.py
+++ b/glhe/aggregation/no_agg.py
@@ -48,6 +48,7 @@ def calc_temporal_superposition(self, time_step: int, _: float = None) -> float:
             # convolution for "g" g-functions only
             return float(np.dot(dq, g))
 
+    # TODO: Should these abstract methods be populated to do anything? If not, should they actually be abstract methods?
     def get_g_value(self, time_step: int) -> float:
         pass  # pragma: no cover
 
diff --git a/glhe/aggregation/static.py b/glhe/aggregation/static.py
index 7d05424e..633f12b9 100644
--- a/glhe/aggregation/static.py
+++ b/glhe/aggregation/static.py
@@ -63,13 +63,14 @@ def aggregate(self, time: int, energy: float):
             # store whatever rolls off of the sub-hourly method
 
             # need to think about this
+            # TODO: If this is returning early, what about the prev_update_time assignments below?
             self.energy[-1] += e_1
             return
         else:
             # aggregate
             # TODO: The next two lines are showing as unused in Pycharm, is this IF block needed then?
             # dts_flip = np.flipud(self.dts)
-            # vals, idxs, cnts = np.unique(dts_flip, return_counts=True, return_index=True)
+            # vals, indexes, counts = np.unique(dts_flip, return_counts=True, return_index=True)
             self.energy[-1] += e_1
 
             # numpy split will do a lot of work too
diff --git a/glhe/ground_temps/base.py b/glhe/ground_temps/base.py
index a18c4722..dd7a25a0 100644
--- a/glhe/ground_temps/base.py
+++ b/glhe/ground_temps/base.py
@@ -7,11 +7,11 @@ class BaseGroundTemp(ABC):
     """
 
     @abstractmethod
-    def get_temp(self, time: int, depth: float):
+    def get_temp(self, time: int, depth: float) -> float:
         """
          Getter method for ground temperatures
 
-        :param time: time for ground temperature [s]
+        :param time: time for ground temperature [s]  # TODO: Should we use float instead of int for time?
         :param depth: depth for ground temperature [m]
         :return: ground temperature [C]
         """
diff --git a/glhe/input_processor/input_processor.py b/glhe/input_processor/input_processor.py
index bdc24a3c..bd33647a 100644
--- a/glhe/input_processor/input_processor.py
+++ b/glhe/input_processor/input_processor.py
@@ -1,4 +1,6 @@
+from json import loads
 import os
+from pathlib import Path
 
 from jsonschema import SchemaError, ValidationError, validate
 
@@ -8,7 +10,7 @@
 
 class InputProcessor:
 
-    def __init__(self, json_input_path: str):
+    def __init__(self, json_input_path: Path):
         """
         Initialize the input processor, process input file, and store the input information.
 
@@ -18,11 +20,11 @@ def __init__(self, json_input_path: str):
         """
 
         # check if file exists
-        if not os.path.exists(json_input_path):
-            raise FileNotFoundError("Input file: '{}' does not exist.".format(json_input_path))
+        if not json_input_path.exists():
+            raise FileNotFoundError(f"Input file: '{json_input_path}' does not exist.")
 
         # load the input file
-        self.input_dict = lower_obj(load_json(json_input_path))
+        self.input_dict: dict = lower_obj(loads(json_input_path.read_text()))
 
         # validate the inputs
         self.validate_inputs(self.input_dict)
diff --git a/glhe/output_processor/output_processor.py b/glhe/output_processor/output_processor.py
index de40b759..1adf37a3 100644
--- a/glhe/output_processor/output_processor.py
+++ b/glhe/output_processor/output_processor.py
@@ -1,20 +1,19 @@
 import datetime as dt
-import os
-from os.path import join, normpath
+from pathlib import Path
 
 import pandas as pd
 
 
 class OutputProcessor:
 
-    def __init__(self, output_dir: str, output_name: str):
+    def __init__(self, output_dir: Path, output_name: str):
         """
         Output processor manages output data
         """
 
         self.output_dir = output_dir
         self.output_file = output_name
-        self.write_path = normpath(join(output_dir, output_name))
+        self.write_path = output_dir / output_name
         self.df = pd.DataFrame()
         self.idx_count = 0
 
@@ -33,11 +32,11 @@ def write_to_file(self) -> None:
         """
         Write the DataFrame holding the simulation data to a file.
         """
-        if os.path.exists(self.write_path):
-            os.remove(self.write_path)
+        if self.write_path.exists():
+            self.write_path.unlink()
 
         self.convert_time_to_timestamp()
-        self.df.to_csv(self.write_path)
+        self.df.to_csv(str(self.write_path))  # TODO: can probably just write it ourselves
 
     def convert_time_to_timestamp(self) -> None:
         """
diff --git a/glhe/profiles/external_base.py b/glhe/profiles/external_base.py
index 26a04494..fca397da 100644
--- a/glhe/profiles/external_base.py
+++ b/glhe/profiles/external_base.py
@@ -1,3 +1,5 @@
+from pathlib import Path
+
 import pandas as pd
 
 from glhe.utilities.functions import Interpolator1D
@@ -5,9 +7,9 @@
 
 class ExternalBase(object):
 
-    def __init__(self, path, col_num):
+    def __init__(self, path: Path, col_num: int):
 
-        df = pd.read_csv(path, index_col=0, parse_dates=True)
+        df = pd.read_csv(str(path), index_col=0, parse_dates=True)
         df['delta t'] = df.index.to_series().diff().dt.total_seconds()
         df['delta t'].iat[0] = 0
         x_range = df['delta t'].cumsum().tolist()
diff --git a/glhe/standalone/plant_loop.py b/glhe/standalone/plant_loop.py
index 715ffa47..6614fbe3 100644
--- a/glhe/standalone/plant_loop.py
+++ b/glhe/standalone/plant_loop.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 
 import datetime as dt
-import os
+from pathlib import Path
 import sys
 
 from glhe.input_processor.component_types import ComponentTypes
@@ -16,7 +16,7 @@
 class PlantLoop:
     Type = ComponentTypes.PlantLoop
 
-    def __init__(self, json_file_path: str):
+    def __init__(self, json_file_path: Path):
         """
         Initialize the plant loop and all components on it.
 
@@ -30,11 +30,11 @@ def __init__(self, json_file_path: str):
 
         try:
             # setup output processor
-            self.op = OutputProcessor(self.ip.input_dict['simulation']['output-path'],
-                                      self.ip.input_dict['simulation']['output-csv-name'])
+            output_path = Path(self.ip.input_dict['simulation']['output-path'])
+            self.op = OutputProcessor(output_path, self.ip.input_dict['simulation']['output-csv-name'])
         except KeyError:
             # paths were not provided. apply default paths.
-            self.op = OutputProcessor(os.getcwd(), 'out.csv')
+            self.op = OutputProcessor(Path.cwd(), 'out.csv')
 
         # init plant-level variables
         self.demand_inlet_temp = self.ip.input_dict['simulation']['initial-temperature']
@@ -86,11 +86,11 @@ def simulate(self) -> bool:
 
         if status:
             print('Simulation time: {}'.format(dt.datetime.now() - self.start_time))
-            with open('{}.txt'.format(os.path.join(self.op.output_dir, self.op.output_file[:-4])), 'w+') as f:
+            with open('{}.txt'.format(self.op.output_dir / self.op.output_file[:-4]), 'w+') as f:
                 f.write('Simulation time: {}\n'.format(dt.datetime.now() - self.start_time))
         else:
             print('Simulation FAILED!')
-            with open('{}.txt'.format(os.path.join(self.op.output_dir, self.op.output_file[:-4])), 'w+') as f:
+            with open('{}.txt'.format(self.op.output_dir / self.op.output_file[:-4]), 'w+') as f:
                 f.write('Simulation FAILED!\n')
 
         return status
@@ -149,7 +149,11 @@ def collect_outputs(self, sim_time):
 
 
 def main():
-    PlantLoop(sys.argv[1]).simulate()
+    p = Path(sys.argv[1])
+    if not p.is_absolute():
+        p = Path.cwd() / p
+    loop = PlantLoop(p)
+    loop.simulate()
 
 
 if __name__ == "__main__":
diff --git a/glhe/utilities/functions.py b/glhe/utilities/functions.py
index d3e9c9d7..4d730e2c 100644
--- a/glhe/utilities/functions.py
+++ b/glhe/utilities/functions.py
@@ -1,5 +1,7 @@
 import json
+from abc import ABC, abstractmethod
 from math import ceil, exp, factorial, floor
+from pathlib import Path
 from typing import Callable, overload
 
 import numpy as np
@@ -218,8 +220,8 @@ def load_json(input_path: str) -> dict:
     return json.loads(json_blob)
 
 
-def write_json(write_path: str, input_dict: dict, indent: int = 2) -> None:
-    with open(write_path, 'w') as f:
+def write_json(write_path: Path, input_dict: dict, indent: int = 2) -> None:
+    with write_path.open('w') as f:
         f.write(json.dumps(input_dict, sort_keys=True, indent=indent, separators=(',', ': ')))
 
 
@@ -468,7 +470,7 @@ def un_reverse_idx(length: int, reversed_idx: int) -> int:
     return length - 1 - reversed_idx
 
 
-def write_arrays_to_csv(path: str, arrays: list | np.ndarray) -> None:
+def write_arrays_to_csv(path: Path, arrays: list | np.ndarray) -> None:
     _arrays = None
     if isinstance(arrays, list):
         _arrays = np.array(arrays)
@@ -477,12 +479,18 @@ def write_arrays_to_csv(path: str, arrays: list | np.ndarray) -> None:
 
     df = pd.DataFrame.from_records(_arrays)
     df = df.T
-    df.to_csv(path, header=False, index=False)
+    df.to_csv(str(path), header=False, index=False)
 
 
-class Interpolator1D:
+class InterpolatorBase(ABC):
+    @abstractmethod
+    def interpolate(self, *args: list[float]) -> float:
+        pass
 
-    def __init__(self, x_data: np.ndarray, y_data: np.ndarray | list[float]):  # TODO: Use pathlib internally everywhere
+
+class Interpolator1D(InterpolatorBase):
+
+    def __init__(self, x_data: np.ndarray, y_data: np.ndarray | list[float]):
         """
         1D Interpolation Class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
 
@@ -491,26 +499,26 @@ def __init__(self, x_data: np.ndarray, y_data: np.ndarray | list[float]):  # TOD
         """
         self.interp = interp1d(x_data, y_data, fill_value='extrapolate')
 
-    def interpolate(self, x: float) -> float:
-        return self.interp(x)
+    def interpolate(self, *args: list[float]) -> float:
+        return self.interp(args[0])
 
 
 class Interpolator1DFromFile(Interpolator1D):
-    def __init__(self, data_path: str):  # TODO: Try to use pathlib internally everywhere
+    def __init__(self, data_path: Path):
         """
         1D Interpolation Class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
 
         :param data_path: path to csv file with columned data, e.g. 'x1,y1'
         """
-        data = np.genfromtxt(data_path, delimiter=',')
+        data = np.genfromtxt(str(data_path), delimiter=',')
         _, num_col = data.shape
         if num_col != 2:
             raise ValueError("Number of columns in '{}' must be 2".format(data_path))
         super().__init__(data[:, 0], data[:, 1])
 
 
-class Interpolator2DFromFile:
-    def __init__(self, xz_data_path: str, y: list):
+class Interpolator2DFromFile(InterpolatorBase):
+    def __init__(self, xz_data_path: Path, y: list):
         """
         2D interpolation class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
 
@@ -532,7 +540,7 @@ def __init__(self, xz_data_path: str, y: list):
         :param y: list of *constant* values for the second independent variable
         """
 
-        data = np.genfromtxt(xz_data_path, delimiter=',')
+        data = np.genfromtxt(str(xz_data_path), delimiter=',')
         _, num_col = data.shape
 
         num_series = num_col - 1
@@ -548,9 +556,9 @@ def __init__(self, xz_data_path: str, y: list):
 
         self.interp = RegularGridInterpolator((x, y), z)
 
-    def interpolate(self, x: float, y: float) -> float:
-        x = self.interp((x, y))
-        return x.min()
+    def interpolate(self, *args: list[float]) -> float:
+        x = self.interp(args)
+        return x.min()  # just want to get the first item, this works fine, but could do better
 
 
 def resample_g_functions(lntts, g, lntts_interval=0.1):
diff --git a/unit_tests/glhe/input_processor/test_input_processor.py b/unit_tests/glhe/input_processor/test_input_processor.py
index 42fedd29..78af5dbd 100644
--- a/unit_tests/glhe/input_processor/test_input_processor.py
+++ b/unit_tests/glhe/input_processor/test_input_processor.py
@@ -1,7 +1,7 @@
 import os
+from pathlib import Path
 import tempfile
 import unittest
-from contextlib import contextmanager
 
 from jsonschema.exceptions import ValidationError
 
@@ -11,20 +11,15 @@
 
 class TestInputProcessor(unittest.TestCase):
 
-    @contextmanager
-    def assertNotRaise(self, exc_type):
-        try:
-            yield None
-        except exc_type:  # pragma: no cover
-            raise self.failureException('{} raised'.format(exc_type.__name__))  # pragma: no cover
-
     def run_validate(self, inputs):
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, inputs)
 
-        with self.assertNotRaise(ValidationError):
+        try:
             InputProcessor(temp_file)
+        except ValidationError:
+            self.fail('Input processor validation failed')
 
     def test_validate_pipe_definitions(self):
         d = {'pipe-definitions': [{
@@ -235,7 +230,8 @@ def test_all_schema_tests_implemented(self):
         self.assertEqual(test_count, schema_count)
 
     def test_file_not_found(self):
-        self.assertRaises(FileNotFoundError, lambda: InputProcessor('some path'))
+        with self.assertRaises(FileNotFoundError):
+            InputProcessor(Path('some path'))
 
     def test_validate_validation_error(self):
         d = {'soil': {'name': 'Some Rock',
@@ -252,9 +248,9 @@ def test_get_definition_object_fail(self):
              'name': 'my name',
              'length': 100}]}
 
-        temp_dir = tempfile.mkdtemp()
-        f_path = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        f_path = temp_dir / 'temp.json'
         write_json(f_path, d)
         ip = InputProcessor(f_path)
-        with self.assertRaises(KeyError) as _:
+        with self.assertRaises(KeyError):
             ip.get_definition_object('pipe-definitions', 'not-implemented')
diff --git a/unit_tests/glhe/input_processor/test_plant_loop_component_factory.py b/unit_tests/glhe/input_processor/test_plant_loop_component_factory.py
index e29f3116..0d57d9cf 100644
--- a/unit_tests/glhe/input_processor/test_plant_loop_component_factory.py
+++ b/unit_tests/glhe/input_processor/test_plant_loop_component_factory.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -12,17 +12,15 @@
 from glhe.topology.pipe import Pipe
 from glhe.utilities.functions import write_json
 
-join = os.path.join
-norm = os.path.normpath
-cwd = os.getcwd()
-
 
 class TestPLCompFactory(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        f_path = os.path.dirname(os.path.abspath(__file__))
-        d = {
+        f_path = Path(__file__).parent
+        root = f_path.parent.parent.parent
+        g_func_file = root / 'validation' / 'MFRTRT_EWT_g_functions' / 'EWT_experimental_g_functions.csv'
+        d: dict = {
             "borehole-definitions": [
                 {
                     "borehole-type": "single-grouted",
@@ -79,10 +77,8 @@ def add_instance():
                 {
                     "name": "GHE 1",
                     "simulation-mode": "enhanced",
-                    "g-function-path": norm(join(f_path, '..', '..', '..', 'validation', 'MFRTRT_EWT_g_functions',
-                                                 'EWT_experimental_g_functions.csv')),
-                    "g_b-function-path": norm(join(f_path, '..', '..', '..', 'validation', 'MFRTRT_EWT_g_functions',
-                                                   'EWT_experimental_g_functions.csv')),
+                    "g-function-path": str(g_func_file),
+                    "g_b-function-path": str(g_func_file),
                     "flow-paths": [
                         {
                             "name": "path 1",
@@ -151,9 +147,9 @@ def add_instance():
             }
         }
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = join(temp_dir, 'in.json')
-        d['simulation']['output-path'] = temp_dir
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'in.json'
+        d['simulation']['output-path'] = str(temp_dir)
         write_json(temp_file, d)
         ip = InputProcessor(temp_file)
         op = OutputProcessor(temp_dir, 'out.csv')
diff --git a/unit_tests/glhe/output_processor/test_output_processor.py b/unit_tests/glhe/output_processor/test_output_processor.py
index 98fad526..386705b1 100644
--- a/unit_tests/glhe/output_processor/test_output_processor.py
+++ b/unit_tests/glhe/output_processor/test_output_processor.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -11,7 +11,7 @@ class TestOutputProcessor(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        temp_dir = tempfile.mkdtemp()
+        temp_dir = Path(tempfile.mkdtemp())
         temp_file_name = 'temp.csv'
         return OutputProcessor(temp_dir, temp_file_name)
 
@@ -36,7 +36,7 @@ def test_write_to_file(self):
         tst.write_to_file()
 
         # check that the file was written
-        self.assertTrue(os.path.exists(tst.write_path))
+        self.assertTrue(tst.write_path.exists())
 
         # make sure the data comes out right
         df = pd.read_csv(tst.write_path)
diff --git a/unit_tests/glhe/profiles/test_constant_flow.py b/unit_tests/glhe/profiles/test_constant_flow.py
index 770d894b..b785d524 100644
--- a/unit_tests/glhe/profiles/test_constant_flow.py
+++ b/unit_tests/glhe/profiles/test_constant_flow.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -15,8 +15,8 @@ class TestConstantFlow(unittest.TestCase):
     def add_instance():
         d = {'flow-profile': [{'flow-profile-type': 'constant', 'name': 'my name', 'value': 0.1}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_constant_load.py b/unit_tests/glhe/profiles/test_constant_load.py
index c50ff610..3775224f 100644
--- a/unit_tests/glhe/profiles/test_constant_load.py
+++ b/unit_tests/glhe/profiles/test_constant_load.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -16,8 +16,8 @@ def add_instance():
         d = {'fluid': {'fluid-type': 'water'},
              'load-profile': [{'load-profile-type': 'constant', 'name': 'my name', 'value': 4000}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_constant_temp.py b/unit_tests/glhe/profiles/test_constant_temp.py
index b829710e..ccb67de1 100644
--- a/unit_tests/glhe/profiles/test_constant_temp.py
+++ b/unit_tests/glhe/profiles/test_constant_temp.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -15,8 +15,8 @@ class TestConstantFlow(unittest.TestCase):
     def add_instance():
         d = {'temperature-profile': [{'temperature-profile-type': 'constant', 'name': 'my name', 'value': 20}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_external_base.py b/unit_tests/glhe/profiles/test_external_base.py
index bde042f8..a7631fcb 100644
--- a/unit_tests/glhe/profiles/test_external_base.py
+++ b/unit_tests/glhe/profiles/test_external_base.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -9,10 +9,10 @@ class TestExternalBase(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        temp_dir = tempfile.mkdtemp()
-        temp_csv = os.path.join(temp_dir, 'temp.csv')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_csv = temp_dir / 'temp.csv'
 
-        with open(temp_csv, 'w') as f:
+        with temp_csv.open('w') as f:
             f.write(',b,c\n1/1/2018 0:00,1,4\n1/1/2018 0:02,2,3\n1/1/2018 0:04,3,6\n')
 
         return ExternalBase(temp_csv, 0)
diff --git a/unit_tests/glhe/profiles/test_external_flow.py b/unit_tests/glhe/profiles/test_external_flow.py
index 21065ee6..08b09b33 100644
--- a/unit_tests/glhe/profiles/test_external_flow.py
+++ b/unit_tests/glhe/profiles/test_external_flow.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -12,11 +12,11 @@
 class TestExternalFlow(unittest.TestCase):
 
     @staticmethod
-    def add_instance(path):
-        d = {'flow-profile': [{'flow-profile-type': 'external', 'name': 'my name', 'path': path}]}
+    def add_instance(path: Path):
+        d = {'flow-profile': [{'flow-profile-type': 'external', 'name': 'my name', 'path': str(path)}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
@@ -26,18 +26,19 @@ def add_instance(path):
         return ExternalFlow(d['flow-profile'][0], ip, op)
 
     def test_get_value(self):
-        dir_name = os.path.dirname(__file__)
-        relative_path = '../../../glhe/profiles/external_data/GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
-        path = os.path.normpath(os.path.join(dir_name, relative_path))
+        dir_name = Path(__file__).parent
+        root_dir = dir_name.parent.parent.parent
+        data_folder = root_dir / 'glhe' / 'profiles' / 'external_data'
+        path = data_folder / 'GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
         tst = self.add_instance(path)
         self.assertEqual(tst.get_value(0), 0)
         self.assertEqual(tst.get_value(10 * 3600), 1)
         self.assertEqual(tst.get_value(8759 * 3600), 0)
 
     def test_start_end_points(self):
-        temp_dir = tempfile.mkdtemp()
-        temp_data = os.path.join(temp_dir, 'temp_data.csv')
-        with open(temp_data, 'w') as f:
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_data = temp_dir / 'temp_data.csv'
+        with temp_data.open('w') as f:
             f.write('Date/Time, Meas. Total Power [W], mdot [kg/s]\n'
                     '2018-01-01 00:00:00, 1, 1\n'
                     '2018-01-01 01:00:00, 2, 2\n'
@@ -53,9 +54,9 @@ def test_start_end_points(self):
         self.assertEqual(tst.get_value(3.0 * 3600), 4.0)
 
     def test_repeated_points(self):
-        temp_dir = tempfile.mkdtemp()
-        temp_data = os.path.join(temp_dir, 'temp_data.csv')
-        with open(temp_data, 'w') as f:
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_data = temp_dir / 'temp_data.csv'
+        with temp_data.open('w') as f:
             f.write('Date/Time, Meas. Total Power [W], mdot [kg/s]\n'
                     '2018-01-01 00:00:00, 1, 1\n'
                     '2018-01-01 01:00:00, 2, 2\n'
@@ -76,9 +77,9 @@ def test_repeated_points(self):
         self.assertEqual(tst.get_value(12.0 * 3600), 1.0)
 
     def test_simulate_time_step(self):
-        temp_dir = tempfile.mkdtemp()
-        temp_data = os.path.join(temp_dir, 'temp_data.csv')
-        with open(temp_data, 'w') as f:
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_data = temp_dir / 'temp_data.csv'
+        with temp_data.open('w') as f:
             f.write('Date/Time, Meas. Total Power [W], mdot [kg/s]\n'
                     '2018-01-01 00:00:00, 1, 1\n'
                     '2018-01-01 01:00:00, 2, 2\n'
@@ -93,9 +94,9 @@ def test_simulate_time_step(self):
         self.assertEqual(res.temperature, 10)
 
     def test_report_outputs(self):
-        temp_dir = tempfile.mkdtemp()
-        temp_data = os.path.join(temp_dir, 'temp_data.csv')
-        with open(temp_data, 'w') as f:
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_data = temp_dir / 'temp_data.csv'
+        with temp_data.open('w') as f:
             f.write('Date/Time, Meas. Total Power [W], mdot [kg/s]\n'
                     '2018-01-01 00:00:00, 1, 1\n'
                     '2018-01-01 01:00:00, 2, 2\n'
diff --git a/unit_tests/glhe/profiles/test_external_load.py b/unit_tests/glhe/profiles/test_external_load.py
index 73cf975b..d8d475d8 100644
--- a/unit_tests/glhe/profiles/test_external_load.py
+++ b/unit_tests/glhe/profiles/test_external_load.py
@@ -1,4 +1,5 @@
 import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -12,12 +13,12 @@
 class TestExternalLoad(unittest.TestCase):
 
     @staticmethod
-    def add_instance(path):
+    def add_instance(path: Path):
         d = {'fluid': {'fluid-type': 'water'},
-             'load-profile': [{'load-profile-type': 'external', 'name': 'my name', 'path': path}]}
+             'load-profile': [{'load-profile-type': 'external', 'name': 'my name', 'path': str(path)}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
@@ -27,9 +28,10 @@ def add_instance(path):
         return ExternalLoad(d['load-profile'][0], ip, op)
 
     def test_get_value(self):
-        dir_name = os.path.dirname(__file__)
-        relative_path = '../../../glhe/profiles/external_data/GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
-        path = os.path.normpath(os.path.join(dir_name, relative_path))
+        dir_name = Path(__file__).parent
+        root_dir = dir_name.parent.parent.parent
+        data_folder = root_dir / 'glhe' / 'profiles' / 'external_data'
+        path = data_folder / 'GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
         tst = self.add_instance(path)
         self.assertEqual(tst.get_value(0), 0)
         self.assertEqual(tst.get_value(10 * 3600), -4980.600013)
diff --git a/unit_tests/glhe/profiles/test_external_temps.py b/unit_tests/glhe/profiles/test_external_temps.py
index df6fa802..6fd2bfed 100644
--- a/unit_tests/glhe/profiles/test_external_temps.py
+++ b/unit_tests/glhe/profiles/test_external_temps.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -13,18 +13,22 @@ class TestExternalTemps(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        temp_dir = tempfile.mkdtemp()
-        temp_data = os.path.join(temp_dir, 'temp_data.csv')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_data = temp_dir / 'temp_data.csv'
 
-        with open(temp_data, 'w') as f:
+        with temp_data.open('w') as f:
             f.write('Date/Time, Meas. Total Power [W], mdot [kg/s], temperature[C]\n'
                     '2018-01-01 00:00:00, 1, 1, 1\n'
                     '2018-01-01 01:00:00, 2, 2, 2\n'
                     '2018-01-01 02:00:00, 3, 3, 3\n'
                     '2018-01-01 03:00:00, 4, 4, 4\n')
 
-        d = {'temperature-profile': [{'temperature-profile-type': 'external', 'name': 'my name', 'path': temp_data}]}
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        d = {
+            'temperature-profile': [
+                {'temperature-profile-type': 'external', 'name': 'my name', 'path': str(temp_data)}
+            ]
+        }
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, d)
 
         ip = InputProcessor(temp_file)
diff --git a/unit_tests/glhe/profiles/test_flow_factory.py b/unit_tests/glhe/profiles/test_flow_factory.py
index e4573764..1a3940a6 100644
--- a/unit_tests/glhe/profiles/test_flow_factory.py
+++ b/unit_tests/glhe/profiles/test_flow_factory.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -15,8 +15,8 @@ class TestFlowFactory(unittest.TestCase):
     def test_constant_flow(self):
         d = {'flow-profile': [{'flow-profile-type': 'constant', 'name': 'my name', 'value': 1}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
@@ -27,17 +27,19 @@ def test_constant_flow(self):
         self.assertIsInstance(tst, ConstantFlow)
 
     def test_external_flow(self):
-        fpath = os.path.dirname(os.path.abspath(__file__))
-        rel_path = '../../../glhe/profiles/external_data/GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
+        dir_name = Path(__file__).parent
+        root_dir = dir_name.parent.parent.parent
+        data_folder = root_dir / 'glhe' / 'profiles' / 'external_data'
+        path = data_folder / 'GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
 
         d = {
             'flow-profile':
                 [{'flow-profile-type': 'external',
                   'name': 'my name',
-                  'path': os.path.join(fpath, rel_path)}]}
+                  'path': str(path)}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
@@ -50,8 +52,8 @@ def test_external_flow(self):
     def test_fail(self):
         d = {'flow-profile': [{'flow-profile-type': 'constant', 'name': 'my name', 'value': 1}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_load_factory.py b/unit_tests/glhe/profiles/test_load_factory.py
index d6f46535..d53f8e79 100644
--- a/unit_tests/glhe/profiles/test_load_factory.py
+++ b/unit_tests/glhe/profiles/test_load_factory.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -17,14 +17,15 @@ class TestLoadFactory(unittest.TestCase):
 
     @staticmethod
     def add_instance(method):
-        fpath = os.path.dirname(os.path.abspath(__file__))
-        data_str = '../../../glhe/profiles/external_data/GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
-        data_path = os.path.normpath(os.path.join(fpath, data_str))
+        fpath = Path(__file__).parent
+        root = fpath.parent.parent.parent
+        data_dir = root / 'glhe' / 'profiles' / 'external_data'
+        data_path = data_dir / 'GSHP-GLHE_USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.csv'
         d = {'fluid': {'fluid-type': 'water'},
              'load-profile': [{'load-profile-type': method,
                                'value': 10,
                                'name': 'my name',
-                               'path': data_path,
+                               'path': str(data_path),
                                'start-time': 1,
                                'end-time': 10,
                                'amplitude': 100,
@@ -32,8 +33,8 @@ def add_instance(method):
                                'period': 10,
                                'synthetic-method': 'symmetric'}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
@@ -68,8 +69,8 @@ def test_fail(self):
                                'value': 10,
                                'name': 'my name'}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_pulse_load.py b/unit_tests/glhe/profiles/test_pulse_load.py
index 8fa7535d..93ae29d7 100644
--- a/unit_tests/glhe/profiles/test_pulse_load.py
+++ b/unit_tests/glhe/profiles/test_pulse_load.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -20,8 +20,8 @@ def add_instance():
                                'start-time': 0,
                                'end-time': 200}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_sinusoid_load.py b/unit_tests/glhe/profiles/test_sinusoid_load.py
index 13e904e7..ca56ab75 100644
--- a/unit_tests/glhe/profiles/test_sinusoid_load.py
+++ b/unit_tests/glhe/profiles/test_sinusoid_load.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -22,8 +22,8 @@ def add_instance():
                                'offset': 0,
                                'period': 2 * pi}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/profiles/test_synthetic_load.py b/unit_tests/glhe/profiles/test_synthetic_load.py
index ae4cd72c..1a300a81 100644
--- a/unit_tests/glhe/profiles/test_synthetic_load.py
+++ b/unit_tests/glhe/profiles/test_synthetic_load.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -19,8 +19,8 @@ def add_instance(method):
                                'amplitude': 1000,
                                'synthetic-method': method}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
 
         write_json(temp_file, d)
 
diff --git a/unit_tests/glhe/properties/test_fluid_types.py b/unit_tests/glhe/properties/test_fluid_types.py
index bc580ad7..f6b7342a 100644
--- a/unit_tests/glhe/properties/test_fluid_types.py
+++ b/unit_tests/glhe/properties/test_fluid_types.py
@@ -6,14 +6,14 @@
 class TestFluidType(unittest.TestCase):
 
     def test_init(self):
-        tst_W = FluidType.WATER
-        self.assertEqual(tst_W, FluidType.WATER)
+        tst_w = FluidType.WATER
+        self.assertEqual(tst_w, FluidType.WATER)
 
-        tst_EA = FluidType.ETHYL_ALCOHOL
-        self.assertEqual(tst_EA, FluidType.ETHYL_ALCOHOL)
+        tst_ea = FluidType.ETHYL_ALCOHOL
+        self.assertEqual(tst_ea, FluidType.ETHYL_ALCOHOL)
 
-        tst_EG = FluidType.ETHYLENE_GLYCOL
-        self.assertEqual(tst_EG, FluidType.ETHYLENE_GLYCOL)
+        tst_eg = FluidType.ETHYLENE_GLYCOL
+        self.assertEqual(tst_eg, FluidType.ETHYLENE_GLYCOL)
 
-        tst_PG = FluidType.PROPYLENE_GLYCOL
-        self.assertEqual(tst_PG, FluidType.PROPYLENE_GLYCOL)
+        tst_pg = FluidType.PROPYLENE_GLYCOL
+        self.assertEqual(tst_pg, FluidType.PROPYLENE_GLYCOL)
diff --git a/unit_tests/glhe/topology/test_ground_heat_exhanger.py b/unit_tests/glhe/topology/test_ground_heat_exhanger.py
index dc71f5ab..c356db32 100644
--- a/unit_tests/glhe/topology/test_ground_heat_exhanger.py
+++ b/unit_tests/glhe/topology/test_ground_heat_exhanger.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -12,7 +12,7 @@ class TestGroundHeatExchanger(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        f_path = os.path.dirname(os.path.abspath(__file__))
+        f_path = Path(__file__).parent
         d = {
             "borehole-definitions": [
                 {
@@ -70,8 +70,8 @@ def add_instance():
                 {
                     "name": "GHE 1",
                     "simulation-mode": "enhanced",
-                    "g-function-path": os.path.join(f_path, '..', '..', '..', 'validation', 'MFRTRT_LTS', 'g.csv'),
-                    "g_b-function-path": os.path.join(f_path, '..', '..', '..', 'validation', 'MFRTRT_LTS', 'g_b.csv'),
+                    "g-function-path": str(f_path.parent.parent.parent / 'validation' / 'MFRTRT_LTS' / 'g.csv'),
+                    "g_b-function-path": str(f_path.parent.parent.parent / 'validation' / 'MFRTRT_LTS' / 'g_b.csv'),
                     "flow-paths": [
                         {
                             "name": "path 1",
@@ -131,8 +131,8 @@ def add_instance():
                 "specific-heat": 880
             }
         }
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, d)
 
         ip = InputProcessor(temp_file)
diff --git a/unit_tests/glhe/topology/test_ground_heat_exhanger_short_time_step.py b/unit_tests/glhe/topology/test_ground_heat_exhanger_short_time_step.py
index 97450d4d..cc280525 100644
--- a/unit_tests/glhe/topology/test_ground_heat_exhanger_short_time_step.py
+++ b/unit_tests/glhe/topology/test_ground_heat_exhanger_short_time_step.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -12,7 +12,8 @@ class TestGroundHeatExchangerShortTimeStep(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        f_path = os.path.dirname(os.path.abspath(__file__))
+        f_path = Path(__file__).parent
+        root_dir = f_path.parent.parent.parent
         d = {
             "borehole-definitions": [
                 {
@@ -70,8 +71,9 @@ def add_instance():
                 {
                     "name": "GHE 1",
                     "simulation-mode": "direct",
-                    "g-function-path": os.path.join(f_path, '..', '..', '..', 'validation', 'MFRTRT_EWT_g_functions',
-                                                    'EWT_experimental_g_functions.csv'),
+                    "g-function-path": str(
+                        root_dir / 'validation' / 'MFRTRT_EWT_g_functions' / 'EWT_experimental_g_functions.csv'
+                    ),
                     "flow-paths": [
                         {
                             "name": "path 1",
@@ -131,8 +133,8 @@ def add_instance():
                 "specific-heat": 880
             }
         }
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, d)
 
         ip = InputProcessor(temp_file)
diff --git a/unit_tests/glhe/topology/test_path.py b/unit_tests/glhe/topology/test_path.py
index 30be723e..1e1ec5a1 100644
--- a/unit_tests/glhe/topology/test_path.py
+++ b/unit_tests/glhe/topology/test_path.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path as PythonPath
 import tempfile
 import unittest
 
@@ -7,14 +7,11 @@
 from glhe.topology.path import Path
 from glhe.utilities.functions import write_json
 
-join = os.path.join
-norm = os.path.normpath
-
 
 class TestPath(unittest.TestCase):
 
     def setUp(self):
-        self.this_file_directory = os.path.dirname(os.path.realpath(__file__))
+        self.this_file_directory = PythonPath(__file__).parent
 
     @staticmethod
     def add_instance():
@@ -100,8 +97,8 @@ def add_instance():
             }
         }
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = norm(join(temp_dir, 'temp.json'))
+        temp_dir = PythonPath(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, d)
         ip = InputProcessor(temp_file)
         op = OutputProcessor(temp_dir, 'out.csv')
diff --git a/unit_tests/glhe/topology/test_pipe.py b/unit_tests/glhe/topology/test_pipe.py
index d81acc9b..d9adcc6b 100644
--- a/unit_tests/glhe/topology/test_pipe.py
+++ b/unit_tests/glhe/topology/test_pipe.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 from math import log
@@ -27,8 +27,8 @@ def add_instance():
                  'name': 'pipe 1',
                  'length': 100}]}
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, inputs)
 
         ip = InputProcessor(temp_file)
diff --git a/unit_tests/glhe/topology/test_single_u_tube_grouted_borehole.py b/unit_tests/glhe/topology/test_single_u_tube_grouted_borehole.py
index 6a34debe..2704f215 100644
--- a/unit_tests/glhe/topology/test_single_u_tube_grouted_borehole.py
+++ b/unit_tests/glhe/topology/test_single_u_tube_grouted_borehole.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import sys
 import tempfile
 import unittest
@@ -58,8 +58,8 @@ def add_instance(inputs: dict = None):
                 'specific-heat': 1000}]
         }
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, d)
 
         ip = InputProcessor(temp_file)
diff --git a/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py b/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py
index ce158a32..ba421335 100644
--- a/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py
+++ b/unit_tests/glhe/topology/test_single_u_tube_grouted_segment.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -37,8 +37,8 @@ def add_instance():
                 'specific-heat': 1900}]
         }
 
-        temp_dir = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, d)
 
         ip = InputProcessor(temp_file)
diff --git a/unit_tests/glhe/topology/test_swedish_heat_pump.py b/unit_tests/glhe/topology/test_swedish_heat_pump.py
index a6da4737..a621ef98 100644
--- a/unit_tests/glhe/topology/test_swedish_heat_pump.py
+++ b/unit_tests/glhe/topology/test_swedish_heat_pump.py
@@ -1,4 +1,4 @@
-import os
+from pathlib import Path
 import tempfile
 import unittest
 
@@ -14,9 +14,9 @@ class TestSwedishHP(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        temp_dir = tempfile.mkdtemp()
+        temp_dir = Path(tempfile.mkdtemp())
 
-        with open(os.path.join(temp_dir, 'temp.csv'), 'w') as f:
+        with (temp_dir / 'temp.csv').open('w') as f:
             f.write('Date/Time,Heating Loads (W),Water Heating Loads (W),Outdoor Air Temperature (C)\n')
             f.write('1/1/2019 0:00,751.231087,0,4\n')
             f.write('1/1/2019 1:00,609.682528,60.515364,5.3\n')
@@ -51,14 +51,14 @@ def add_instance():
                                          'outdoor-air-temperature-at-max-heating-set-point': -10,
                                          'outdoor-air-temperature-at-min-heating-set-point': 20,
                                          'immersion-heater-capacity': 7000,
-                                         'load-data-path': os.path.join(temp_dir, 'temp.csv'),
+                                         'load-data-path': str(temp_dir / 'temp.csv'),
                                          'capacity-coefficients': [8.536666667, -0.007266667,
                                                                    -0.00084, 0.263666667],
                                          'coefficient-of-performance-coefficients': [7.641839817, -0.075098454,
                                                                                      -0.000208441, 0.109423218],
                                          }]}
 
-        temp_file = os.path.join(temp_dir, 'temp.json')
+        temp_file = temp_dir / 'temp.json'
         write_json(temp_file, inputs)
 
         ip = InputProcessor(temp_file)
@@ -70,7 +70,7 @@ def test_init(self):
         tst = self.add_instance()
         self.assertIsInstance(tst, SwedishHP)
 
-    def test_set_htg_exft(self):
+    def test_set_htg_exiting_ft(self):
         tst = self.add_instance()
         tol = 0.001
         # checked against JDS VBA code
diff --git a/unit_tests/glhe/utilities/test_functions.py b/unit_tests/glhe/utilities/test_functions.py
index 205cac17..b4444f70 100644
--- a/unit_tests/glhe/utilities/test_functions.py
+++ b/unit_tests/glhe/utilities/test_functions.py
@@ -1,11 +1,11 @@
-import os
+from json import loads
+from pathlib import Path
 import tempfile
 import unittest
 
 from math import cos, sin
 from numpy import arange, array
 from numpy.linalg import solve as lin_alg_solve
-from scipy.interpolate import interp2d
 
 from glhe.utilities.functions import c_to_k
 from glhe.utilities.functions import hanby
@@ -14,7 +14,6 @@
 from glhe.utilities.functions import lin_interp
 from glhe.utilities.functions import Interpolator1DFromFile
 from glhe.utilities.functions import Interpolator2DFromFile
-from glhe.utilities.functions import load_json
 from glhe.utilities.functions import lower_obj
 from glhe.utilities.functions import merge_dicts
 from glhe.utilities.functions import num_ts_per_hour_to_sec_per_ts
@@ -53,19 +52,19 @@ def test_set_time_step(self):
         self.assertEqual(num_ts_per_hour_to_sec_per_ts(1), 3600)
 
     def test_load_json(self):
-        temp_directory = tempfile.mkdtemp()
-        temp_json_file = os.path.join(temp_directory, 'temp.json')
-        with open(temp_json_file, 'w') as f:
+        temp_directory = Path(tempfile.mkdtemp())
+        temp_json_file = temp_directory / 'temp.json'
+        with temp_json_file.open('w') as f:
             f.write('{"key": "value", "key 2": 1}')
 
-        d = load_json(temp_json_file)
+        d = loads(temp_json_file.read_text())
 
         self.assertEqual(d["key"], "value")
         self.assertEqual(d["key 2"], 1)
 
     def test_write_json(self):
-        temp_directory = tempfile.mkdtemp()
-        temp_file = os.path.join(temp_directory, 'temp.json')
+        temp_directory = Path(tempfile.mkdtemp())
+        temp_file = temp_directory / 'temp.json'
 
         d = {
             "key": "value",
@@ -73,7 +72,7 @@ def test_write_json(self):
         }
 
         write_json(temp_file, d)
-        loaded = load_json(temp_file)
+        loaded = loads(temp_file.read_text())
         self.assertEqual(d, loaded)
 
     def test_hanby(self):
@@ -217,9 +216,9 @@ def test_lin_interp(self):
         self.assertEqual(lin_interp(2, 0, 2, 0, 2), 2)
 
     def test_write_arrays_to_csv(self):
-        temp_dir = tempfile.mkdtemp()
+        temp_dir = Path(tempfile.mkdtemp())
         file_name = 'out.csv'
-        path = os.path.join(temp_dir, file_name)
+        path = temp_dir / file_name
         a_1 = [1, 2, 3]
         a_2 = [4, 5, 6]
         write_arrays_to_csv(path, [a_1, a_2])
@@ -259,9 +258,9 @@ class TestInterp1D(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        temp_dir = tempfile.mkdtemp()
-        f_path = os.path.join(temp_dir, 'temp.csv')
-        with open(f_path, 'w') as f:
+        temp_dir = Path(tempfile.mkdtemp())
+        f_path = temp_dir / 'temp.csv'
+        with f_path.open('w') as f:
             f.write('0,5\n')
             f.write('1,6\n')
             f.write('2,7\n')
@@ -280,9 +279,9 @@ class TestInterp2D(unittest.TestCase):
 
     @staticmethod
     def add_instance():
-        temp_dir = tempfile.mkdtemp()
-        f_path = os.path.join(temp_dir, 'temp.csv')
-        with open(f_path, 'w') as f:
+        temp_dir = Path(tempfile.mkdtemp())
+        f_path = temp_dir / 'temp.csv'
+        with f_path.open('w') as f:
             f.write('0,5,8\n')
             f.write('1,6,9\n')
             f.write('2,7,10\n')
diff --git a/unit_tests/standalone/test_plant_loop.py b/unit_tests/standalone/test_plant_loop.py
index 6b8cad46..038f5654 100644
--- a/unit_tests/standalone/test_plant_loop.py
+++ b/unit_tests/standalone/test_plant_loop.py
@@ -1,28 +1,25 @@
-import os
+from json import loads
+from pathlib import Path
 import tempfile
 import unittest
 
-from glhe.utilities.functions import load_json
 from glhe.utilities.functions import write_json
 from glhe.standalone.plant_loop import PlantLoop
 
-norm = os.path.normpath
-join = os.path.join
-
 
 class TestPlantLoop(unittest.TestCase):
 
     def setUp(self):
-        self.this_file_directory = os.path.dirname(os.path.realpath(__file__))
+        self.this_file_directory = Path(__file__).parent
 
     def test_simulate(self):
-        temp_dir = tempfile.mkdtemp()
-        temp_file = join(temp_dir, 'in.json')
-        input_path = norm(join(self.this_file_directory, '..', '..', 'test_files', 'single.json'))
-        d = load_json(input_path)
-        g_path = norm(join(self.this_file_directory, '..', '..', 'test_files', 'single_g_functions.csv'))
-        d['ground-heat-exchanger'][0]['g-function-path'] = g_path
-        d['simulation']['output-path'] = temp_dir
+        temp_dir = Path(tempfile.mkdtemp())
+        temp_file = temp_dir / 'in.json'
+        input_path = self.this_file_directory.parent.parent / 'test_files' / 'single.json'
+        d = loads(input_path.read_text())
+        g_path = self.this_file_directory.parent.parent / 'test_files' / 'single_g_functions.csv'
+        d['ground-heat-exchanger'][0]['g-function-path'] = str(g_path)
+        d['simulation']['output-path'] = str(temp_dir)
         write_json(temp_file, d)
         p = PlantLoop(temp_file)
         self.assertTrue(p.simulate())

From f48ac14bb204d0b563225667ec74399e1fe1a269 Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Mon, 15 Apr 2024 16:08:38 -0500
Subject: [PATCH 3/8] Eliminated pandas from external_base

---
 glhe/profiles/external_base.py | 66 +++++++++++++++++++++++++++-------
 glhe/utilities/functions.py    | 10 +++---
 2 files changed, 59 insertions(+), 17 deletions(-)

diff --git a/glhe/profiles/external_base.py b/glhe/profiles/external_base.py
index fca397da..79b346aa 100644
--- a/glhe/profiles/external_base.py
+++ b/glhe/profiles/external_base.py
@@ -1,27 +1,69 @@
 from pathlib import Path
 
-import pandas as pd
-
+import csv
+from datetime import datetime
 from glhe.utilities.functions import Interpolator1D
 
 
 class ExternalBase(object):
 
     def __init__(self, path: Path, col_num: int):
-
-        df = pd.read_csv(str(path), index_col=0, parse_dates=True)
-        df['delta t'] = df.index.to_series().diff().dt.total_seconds()
-        df['delta t'].iat[0] = 0
-        x_range = df['delta t'].cumsum().tolist()
-        y_range = df.iloc[:, col_num].tolist()
-
+        x_range, y_range = self.read_csv_and_compute_delta_t(path, col_num)
         # added to allow multi-year simulations
         self.max_time = 0
-        x_range.append(x_range[-1] + (x_range[-1] - x_range[-2]))
-        y_range.append(y_range[0])
         self.max_time = x_range[-1]
-
         self._interp_values = Interpolator1D(x_range, y_range)
 
+    @staticmethod
+    def read_csv_and_compute_delta_t(file_path: Path, col_num: int) -> [list, list]:
+        delta_t_values = []
+        y_values = []
+        last_timestamp = None
+
+        # Open CSV file and read data
+        with open(file_path, 'r') as csvfile:
+            csvreader = csv.reader(csvfile)
+            next(csvreader)  # Read header
+
+            for row in csvreader:
+                timestamp_str = row[0]
+
+                # Convert timestamp string to datetime object
+                current_timestamp = None
+                time_stamp_formats = ['%Y-%m-%d %H:%M:%S', '%m/%d/%Y %H:%M', '%m/%d/%Y %H:%M:%S']
+                for t in time_stamp_formats:
+                    try:
+                        current_timestamp = datetime.strptime(timestamp_str, t)
+                        break
+                    except ValueError:
+                        continue
+                if not current_timestamp:
+                    raise ValueError(f"Bad timestamp format for timestamp: {timestamp_str}")
+
+                if last_timestamp is not None:
+                    # Calculate delta t in seconds
+                    delta_t = (current_timestamp - last_timestamp).total_seconds()
+                    delta_t_values.append(delta_t)
+
+                # Append value to y_values
+                y_values.append(row[col_num + 1])
+
+                last_timestamp = current_timestamp
+
+        # Initialize x_range with cumulative sum of delta_t_values
+        x_range = [0]
+        cumulative_sum = 0
+        for delta_t in delta_t_values:
+            cumulative_sum += delta_t
+            x_range.append(cumulative_sum)
+
+        # Append an extrapolated value to x_range
+        x_range.append(x_range[-1] + (x_range[-1] - x_range[-2]))
+
+        # Append the first y_value to y_range
+        y_values.append(y_values[0])
+
+        return x_range, y_values
+
     def get_value(self, time) -> float:
         return float(self._interp_values.interpolate(time % self.max_time))
diff --git a/glhe/utilities/functions.py b/glhe/utilities/functions.py
index 4d730e2c..58467bfb 100644
--- a/glhe/utilities/functions.py
+++ b/glhe/utilities/functions.py
@@ -1,3 +1,4 @@
+import csv
 import json
 from abc import ABC, abstractmethod
 from math import ceil, exp, factorial, floor
@@ -5,7 +6,6 @@
 from typing import Callable, overload
 
 import numpy as np
-import pandas as pd
 from scipy.interpolate import RegularGridInterpolator
 from scipy.interpolate import interp1d
 
@@ -476,10 +476,10 @@ def write_arrays_to_csv(path: Path, arrays: list | np.ndarray) -> None:
         _arrays = np.array(arrays)
     else:
         _arrays = arrays
-
-    df = pd.DataFrame.from_records(_arrays)
-    df = df.T
-    df.to_csv(str(path), header=False, index=False)
+    data = _arrays.T
+    with open(path, 'w') as f:
+        writer = csv.writer(f)
+        writer.writerows(data)
 
 
 class InterpolatorBase(ABC):

From a4521d5c7009f11467e5e1836c42a63868cc8432 Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Mon, 15 Apr 2024 16:43:49 -0500
Subject: [PATCH 4/8] Eliminate Pandas from required dependencies

---
 glhe/output_processor/output_processor.py     | 37 ++++++++++++-------
 requirements.txt                              |  8 +++-
 setup.py                                      |  3 +-
 .../output_processor/test_output_processor.py | 19 ++++++----
 4 files changed, 44 insertions(+), 23 deletions(-)

diff --git a/glhe/output_processor/output_processor.py b/glhe/output_processor/output_processor.py
index 1adf37a3..fd78d693 100644
--- a/glhe/output_processor/output_processor.py
+++ b/glhe/output_processor/output_processor.py
@@ -1,8 +1,6 @@
 import datetime as dt
 from pathlib import Path
 
-import pandas as pd
-
 
 class OutputProcessor:
 
@@ -14,7 +12,8 @@ def __init__(self, output_dir: Path, output_name: str):
         self.output_dir = output_dir
         self.output_file = output_name
         self.write_path = output_dir / output_name
-        self.df = pd.DataFrame()
+        # self.df = pd.DataFrame()
+        self.output_data = []
         self.idx_count = 0
 
     def collect_output(self, data_dict: dict) -> None:
@@ -23,10 +22,10 @@ def collect_output(self, data_dict: dict) -> None:
 
         :param data_dict: dictionary of data to be logged
         """
-
-        df_temp = pd.DataFrame(data_dict, index=[self.idx_count])
-        self.df = pd.concat([self.df, df_temp], axis=0, sort=True)
-        self.idx_count += 1
+        self.output_data.append(data_dict)
+        # df_temp = pd.DataFrame(data_dict, index=[self.idx_count])
+        # self.df = pd.concat([self.df, df_temp], axis=0, sort=True)
+        # self.idx_count += 1
 
     def write_to_file(self) -> None:
         """
@@ -35,18 +34,28 @@ def write_to_file(self) -> None:
         if self.write_path.exists():
             self.write_path.unlink()
 
-        self.convert_time_to_timestamp()
-        self.df.to_csv(str(self.write_path))  # TODO: can probably just write it ourselves
+        header_row = ['Date/Time']
+        header_row.extend([key for key in sorted(self.output_data[0].keys()) if key != 'Elapsed Time [s]'])
+
+        time_stamps = self.convert_time_to_timestamp()
+        with self.write_path.open('w') as f:
+            for i, d in enumerate(self.output_data):
+                if i == 0:
+                    f.write(','.join(header_row) + '\n')
+                row = [time_stamps[i]]
+                sorted_values_without_time = [str(d[key]) for key in sorted(d.keys()) if key != 'Elapsed Time [s]']
+                row.extend(sorted_values_without_time)
+                f.write(','.join(row) + '\n')
 
-    def convert_time_to_timestamp(self) -> None:
+    def convert_time_to_timestamp(self) -> list[str]:
         """
         Convert the 'Elapsed Time' column to a standardized date/time format.
         """
         try:
-            dts = [dt.timedelta(seconds=x) for x in self.df['Elapsed Time [s]'].values.tolist()]
+            raw_dts = [d['Elapsed Time [s]'] for d in self.output_data]
+            dts = [dt.timedelta(seconds=x) for x in raw_dts]
             start_time = dt.datetime(year=dt.datetime.now().year, month=1, day=1, hour=0, minute=0)
-            time_stamps = [start_time + x for x in dts]
-            self.df['Date/Time'] = time_stamps
-            self.df.set_index('Date/Time', inplace=True)
+            time_stamps = [str(start_time + x) for x in dts]
+            return time_stamps
         except KeyError:
             pass
diff --git a/requirements.txt b/requirements.txt
index f7f28901..e279ecfb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,10 +2,15 @@
 CoolProp
 jsonschema
 numpy
-pandas
 pygfunction
 scipy
 
+###### AFTER THIS LINE ARE OPTIONAL DEVELOPER DEPENDENCIES ######
+######### KEEP THE LINE SAYING "OPTIONAL" IN PLACE HERE #########
+######### IT IS USED BY SETUP.PY WHEN BUILDING PACKAGES #########
+
+# OPTIONAL #
+
 # Dependencies needed to build wheels for PyPi
 wheel
 
@@ -18,6 +23,7 @@ pytest
 flake8
 coverage
 coveralls
+pandas
 
 # Dependencies needed for running the extra validation studies and such
 matplotlib
diff --git a/setup.py b/setup.py
index 3cf49f17..8d4eded7 100755
--- a/setup.py
+++ b/setup.py
@@ -4,7 +4,8 @@
 setup_py_file = Path(__file__).resolve()
 repo_root = setup_py_file.parent
 requirements_path = repo_root / 'requirements.txt'
-requirements = requirements_path.read_text().strip().splitlines()
+requirements_contents = requirements_path.read_text().split('# OPTIONAL #')[0]
+requirements = requirements_contents.strip().splitlines()
 
 setup(
     name='GLHE',
diff --git a/unit_tests/glhe/output_processor/test_output_processor.py b/unit_tests/glhe/output_processor/test_output_processor.py
index 386705b1..78dbb008 100644
--- a/unit_tests/glhe/output_processor/test_output_processor.py
+++ b/unit_tests/glhe/output_processor/test_output_processor.py
@@ -1,4 +1,5 @@
 from pathlib import Path
+from datetime import datetime, timedelta
 import tempfile
 import unittest
 
@@ -23,14 +24,13 @@ def test_collect_output(self):
 
         tst.collect_output(d)
 
-        self.assertEqual(tst.df['foo'][0], 1)
-        self.assertEqual(tst.df['bar'][0], 2)
+        self.assertEqual(tst.output_data[0]['foo'], 1)
+        self.assertEqual(tst.output_data[0]['bar'], 2)
 
     def test_write_to_file(self):
         tst = self.add_instance()
 
-        d = {'foo': 1,
-             'bar': 2}
+        d = {'Elapsed Time [s]': 60, 'foo': 1, 'bar': 2}
 
         tst.collect_output(d)
         tst.write_to_file()
@@ -51,6 +51,11 @@ def test_write_to_file(self):
 
     def test_convert_time_to_timestamp(self):
         tst = self.add_instance()
-        tst.df = pd.DataFrame({'Elapsed Time [s]': [0, 60, 120], 'Variable': [1, 2, 3]})
-        tst.convert_time_to_timestamp()
-        self.assertTrue(tst.df.index.name == 'Date/Time')
+        tst.output_data = [
+            {'Elapsed Time [s]': 0, 'Variable': 1},
+            {'Elapsed Time [s]': 60, 'Variable': 2},
+            {'Elapsed Time [s]': 120, 'Variable': 3},
+        ]
+        time_stamps = tst.convert_time_to_timestamp()
+        date_times = [datetime.strptime(ts, "%Y-%m-%d %H:%M:%S") for ts in time_stamps]
+        self.assertEqual(date_times[1] - date_times[0], timedelta(minutes=1))

From 0945bce042d0d8b6c327dca3af7e905dfffdec20 Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Mon, 15 Apr 2024 16:50:08 -0500
Subject: [PATCH 5/8] Add comment placeholder for using our own RK45 integrator
 on the u-tube segment; one step closer to eliminating scipy

---
 glhe/topology/single_u_tube_grouted_segment.py | 2 ++
 glhe/utilities/functions.py                    | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/glhe/topology/single_u_tube_grouted_segment.py b/glhe/topology/single_u_tube_grouted_segment.py
index 497497e3..99e5d518 100644
--- a/glhe/topology/single_u_tube_grouted_segment.py
+++ b/glhe/topology/single_u_tube_grouted_segment.py
@@ -8,6 +8,7 @@
 from glhe.output_processor.report_types import ReportTypes
 from glhe.properties.base_properties import PropertiesBase
 from glhe.topology.pipe import Pipe
+# from glhe.utilities.functions import runge_kutta_fourth_y
 
 
 @dataclass
@@ -160,6 +161,7 @@ def simulate_time_step(self, time_step: float, inputs: TimeStepStructure) -> np.
         solver = RK45(self.right_hand_side, 0, self.y, time_step)
         while solver.status != 'finished':
             solver.step()
+        # solver_2 = runge_kutta_fourth_y(self.right_hand_side, time_step, self.y)
         self.y = solver.y
 
         # update report vars
diff --git a/glhe/utilities/functions.py b/glhe/utilities/functions.py
index 58467bfb..fe300f83 100644
--- a/glhe/utilities/functions.py
+++ b/glhe/utilities/functions.py
@@ -492,7 +492,7 @@ class Interpolator1D(InterpolatorBase):
 
     def __init__(self, x_data: np.ndarray, y_data: np.ndarray | list[float]):
         """
-        1D Interpolation Class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
+        1D Interpolation Class, currently a wrapper for sci py interpolator, but soon just a simple interpolator
 
         :param x_data: Numpy array of x-value floats
         :param y_data: Numpy array of x-value floats
@@ -506,7 +506,7 @@ def interpolate(self, *args: list[float]) -> float:
 class Interpolator1DFromFile(Interpolator1D):
     def __init__(self, data_path: Path):
         """
-        1D Interpolation Class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
+        1D Interpolation Class, currently a wrapper for sci py interpolator, but soon just a simple interpolator
 
         :param data_path: path to csv file with columned data, e.g. 'x1,y1'
         """
@@ -520,7 +520,7 @@ def __init__(self, data_path: Path):
 class Interpolator2DFromFile(InterpolatorBase):
     def __init__(self, xz_data_path: Path, y: list):
         """
-        2D interpolation class, currently a wrapper for scipy interpolator, but soon just a simple interpolator
+        2D interpolation class, currently a wrapper for sci py interpolator, but soon just a simple interpolator
 
         Example data:
         x1, y1, z1, x2, y2, z2

From 338458294e2c13fd58599fbfe6a446d4f3c5645c Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Tue, 16 Apr 2024 09:14:00 -0500
Subject: [PATCH 6/8] Trim whitespace from csv before reading

---
 unit_tests/glhe/utilities/test_functions.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/unit_tests/glhe/utilities/test_functions.py b/unit_tests/glhe/utilities/test_functions.py
index b4444f70..338d3ec9 100644
--- a/unit_tests/glhe/utilities/test_functions.py
+++ b/unit_tests/glhe/utilities/test_functions.py
@@ -225,7 +225,7 @@ def test_write_arrays_to_csv(self):
 
         with open(path, 'r') as f:
             for idx, line in enumerate(f):
-                tokens = line.split(',')
+                tokens = line.strip().split(',')
                 self.assertEqual(float(tokens[0]), a_1[idx])
                 self.assertEqual(float(tokens[1]), a_2[idx])
 

From b4e25b7e355d460442b7e7380a40b2de32656926 Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Tue, 16 Apr 2024 09:20:20 -0500
Subject: [PATCH 7/8] Maybe it is a blank line causing problems

---
 unit_tests/glhe/utilities/test_functions.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/unit_tests/glhe/utilities/test_functions.py b/unit_tests/glhe/utilities/test_functions.py
index 338d3ec9..5c0025db 100644
--- a/unit_tests/glhe/utilities/test_functions.py
+++ b/unit_tests/glhe/utilities/test_functions.py
@@ -225,6 +225,8 @@ def test_write_arrays_to_csv(self):
 
         with open(path, 'r') as f:
             for idx, line in enumerate(f):
+                if line.strip() == '':
+                    break
                 tokens = line.strip().split(',')
                 self.assertEqual(float(tokens[0]), a_1[idx])
                 self.assertEqual(float(tokens[1]), a_2[idx])

From 0f246da68b7ca3d0cc3a524e09adf1b8d018b6c9 Mon Sep 17 00:00:00 2001
From: Edwin Lee <leeed2001@gmail.com>
Date: Tue, 16 Apr 2024 09:30:13 -0500
Subject: [PATCH 8/8] Stripped whitespace in another spot

---
 unit_tests/glhe/utilities/test_functions.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/unit_tests/glhe/utilities/test_functions.py b/unit_tests/glhe/utilities/test_functions.py
index 5c0025db..f8cd7b43 100644
--- a/unit_tests/glhe/utilities/test_functions.py
+++ b/unit_tests/glhe/utilities/test_functions.py
@@ -239,7 +239,9 @@ def test_write_arrays_to_csv(self):
 
         with open(path, 'r') as f:
             for idx, line in enumerate(f):
-                tokens = line.split(',')
+                if line.strip() == '':
+                    break
+                tokens = line.strip().split(',')
                 self.assertEqual(float(tokens[0]), a_1[idx])
                 self.assertEqual(float(tokens[1]), a_2[idx])