How to make a map with ggmap, ggplot2, and a shape file

mannheim.R

library(pacman)
p_load(tidyverse)
p_load(broom)
p_load(ggmap)
p_load(rgdal)

# For map behind plot ----

# Longitude and latidue
mannheim_longlat <- c(left = 8.38, bottom = 49.4, right = 8.62, top = 49.6)

# Download map from maps.stamen.com
mannmap <- get_stamenmap(mannheim_longlat, zoom = 13, maptype = "terrain")

# Read shape file ----
mannheim_shp <- readOGR("data/mannheim.shp", use_iconv = TRUE, encoding = "UTF-8")

# Tidy shape file
mannheim_tidy <- tidy(mannheim_shp)

# ggplot
ggmap(mannmap) +
  geom_polygon(data = mannheim_tidy, 
               aes(x = long, y = lat, group = group),
               color = "darkgreen",
               fill = "green", 
               alpha = 0.3)