add LRU cache to structure matcher (#4036)

* add LRU cache to  _get_reduced_structure computations

* pre-commit auto-fixes

* make structure hashable via as_dict

* make structure hash recursive as_dict, change structure test to check hashability

* precommit

* moved computation using lru_cache out of class method to avoid memory leakage issue

* pre-commit auto-fixes

* fix structure matcher caching, fix a few tests (mcsqs wrong file destination and missing pytest approx in TestBSPlot)

* precommit

* add suggested SiteOrderedIStructure from @kbuma

* pre-commit auto-fixes

* add cast in eq for SiteOrderedIStructure to make mypy happy

* pre-commit auto-fixes

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: esoteric-ephemera <aaron.kaplan.physics@gmail.com>

src/pymatgen/analysis/structure_matcher.py

@@ -4,12 +4,13 @@
 
 import abc
 import itertools
-from typing import TYPE_CHECKING
+from functools import lru_cache
+from typing import TYPE_CHECKING, cast
 
 import numpy as np
 from monty.json import MSONable
 
-from pymatgen.core import Composition, Lattice, Structure, get_el_sp
+from pymatgen.core import SETTINGS, Composition, IStructure, Lattice, Structure, get_el_sp
 from pymatgen.optimization.linear_assignment import LinearAssignment
 from pymatgen.util.coord import lattice_points_in_supercell
 from pymatgen.util.coord_cython import is_coord_subset_pbc, pbc_shortest_vectors
@@ -29,6 +30,31 @@
 __email__ = "wrichard@mit.edu"
 __status__ = "Production"
 __date__ = "Dec 3, 2012"
+LRU_CACHE_SIZE = SETTINGS.get("STRUCTURE_MATCHER_CACHE_SIZE", 300)
+
+
+class SiteOrderedIStructure(IStructure):
+    """
+    Imutable structure where the order of sites matters.
+
+    In caching reduced structures (see `StructureMatcher._get_reduced_structure`)
+    the order of input sites can be important.
+    In general, the order of sites in a structure does not matter, but when
+    a method like `StructureMatcher.get_s2_like_s1` tries to put s2's sites in
+    the same order as s1, the site order matters.
+    """
+
+    def __eq__(self, other: object) -> bool:
+        """Check for IStructure equality and same site order."""
+        if not super().__eq__(other):
+            return False
+        other = cast(SiteOrderedIStructure, other)  # make mypy happy
+
+        return list(self.sites) == list(other.sites)
+
+    def __hash__(self) -> int:
+        """Use the composition hash for now."""
+        return super().__hash__()
 
 
 class AbstractComparator(MSONable, abc.ABC):
@@ -939,16 +965,26 @@ def _anonymous_match(
                     break
         return matches
 
-    @classmethod
-    def _get_reduced_structure(cls, struct: Structure, primitive_cell: bool = True, niggli: bool = True) -> Structure:
-        """Helper method to find a reduced structure."""
+    @staticmethod
+    @lru_cache(maxsize=LRU_CACHE_SIZE)
+    def _get_reduced_istructure(
+        struct: SiteOrderedIStructure, primitive_cell: bool = True, niggli: bool = True
+    ) -> SiteOrderedIStructure:
+        """Helper method to find a reduced imutable structure."""
         reduced = struct.copy()
         if niggli:
             reduced = reduced.get_reduced_structure(reduction_algo="niggli")
         if primitive_cell:
             reduced = reduced.get_primitive_structure()
         return reduced
 
+    @classmethod
+    def _get_reduced_structure(cls, struct: Structure, primitive_cell: bool = True, niggli: bool = True) -> Structure:
+        """Helper method to find a reduced structure."""
+        return Structure.from_sites(
+            cls._get_reduced_istructure(SiteOrderedIStructure.from_sites(struct), primitive_cell, niggli)
+        )
+
     def get_rms_anonymous(self, struct1, struct2):
         """
         Performs an anonymous fitting, which allows distinct species in one

tests/electronic_structure/test_plotter.py

@@ -153,7 +153,7 @@ def test_bs_plot_data(self):
 
     def test_get_ticks(self):
         assert self.plotter.get_ticks()["label"][5] == "K", "wrong tick label"
-        assert self.plotter.get_ticks()["distance"][5] == 2.406607625322699, "wrong tick distance"
+        assert self.plotter.get_ticks()["distance"][5] == pytest.approx(2.406607625322699), "wrong tick distance"
 
     # Minimal baseline testing for get_plot. not a true test. Just checks that
     # it can actually execute.

tests/transformations/test_advanced_transformations.py

@@ -594,7 +594,7 @@ def test_apply_transformation(self):
 @pytest.mark.skipif(not mcsqs_cmd, reason="mcsqs not present.")
 class TestSQSTransformation(PymatgenTest):
     def test_apply_transformation(self):
-        pzt_structs = loadfn(f"{TEST_FILES_DIR}/mcsqs/pzt-structs.json")
+        pzt_structs = loadfn(f"{TEST_FILES_DIR}/io/atat/mcsqs/pzt-structs.json")
         trans = SQSTransformation(scaling=[2, 1, 1], search_time=0.01, instances=1, wd=0)
         # nonsensical example just for testing purposes
         struct = self.get_structure("Pb2TiZrO6").copy()
@@ -605,7 +605,7 @@ def test_apply_transformation(self):
 
     def test_return_ranked_list(self):
         # list of structures
-        pzt_structs_2 = loadfn(f"{TEST_FILES_DIR}/mcsqs/pzt-structs-2.json")
+        pzt_structs_2 = loadfn(f"{TEST_FILES_DIR}/io/atat/mcsqs/pzt-structs-2.json")
 
         n_structs_expected = 1
         sqs_kwargs = {"scaling": 2, "search_time": 0.01, "instances": 8, "wd": 0}