choropleth_map_demo.Rmd

---
title: "Choropleth Map Demo"
header-includes: 
 \usepackage{geometry}
 \geometry{top=0.75in,left=0.75in,bottom=0.75in,right=0.75in}
mainfont: Arial
output:
  pdf_document:
    latex_engine: xelatex
---

```{r, echo=FALSE, message=FALSE, warning=FALSE}
# load libraries
library(knitr)
library(tidyverse)
library(mapdata)
library(maps)
library(stringr)
```

```{r, echo=FALSE, message=FALSE, warning=FALSE}
# wrangle data
wi_state <- map_data("state") %>% filter(region == "wisconsin")
wi_counties <- map_data("county") %>% filter(region == "wisconsin")
```

```{r, echo=FALSE, message=FALSE, warning=FALSE}
# build base layer
map_base_layer <- ggplot(
  # plot state outline
  data = wi_state, mapping = aes(x = long, y = lat, group = group)) +
  coord_quickmap() +
  theme_void() +
  geom_polygon(color = "black", fill = "#999999") +
  # plot county outlines
  geom_polygon(data = wi_counties, fill = NA, color = "black") +
  geom_polygon(color = "black", fill = NA)
```

```{r, echo=FALSE, message=FALSE, warning=FALSE, fig.align='center', fig.width=6, fig.height=6}
# plot points layer
wi_schools <- read.csv("choropleth_map_demo_data.csv", header = TRUE)
map_with_points <- map_base_layer +
  ggtitle(label = "IPEDS Schools in Wisconsin") +
  geom_point(data = wi_schools, inherit.aes = FALSE,
  alpha = 0.75, color = "#147536", size = 5,
  mapping = aes(x = LONGITUD, y = LATITUDE)) +
  theme(legend.position = "none")
# display plot with points
map_with_points
```
\newpage

```{r, echo=FALSE, message=FALSE, warning=FALSE, fig.align='center', fig.width=6, fig.height=6}
# recolor points layer to indicate sector
map_with_points <- map_base_layer +
  ggtitle(label = "IPEDS Schools in Wisconsin, by Sector") +
  geom_point(data = wi_schools, inherit.aes = FALSE,
  alpha = 0.75, size = 5,
  mapping = aes(x = LONGITUD, y = LATITUDE, color = SECTOR)) +
  theme(legend.position = "right")
# display plot with points
map_with_points
```