Count the number of MRT/LRT stations in each postal district

sg_mrt_per_district.R

library(sp)
library(rgdal)

# better to download & read the files programmatically, but something
#   funky is happening on that route, not bothering to debug too deeply.
# for reproducibility:
#   (1) Click Download at the URL
#   (2) Unzip the file; it contains two more zip directories, one KML and one SHP
#   (3) Unzip the .shp zip to ~/Downloads/mrt

# via https://data.gov.sg/dataset/master-plan-2014-rail-station
mrt = rgdal::readOGR("~/Downloads/mrt", "G_MP14_RAIL_STN_PL")

# NB: I hand-drew this in the Maps interface & exported to KML
districts = rgdal::readOGR("~/Downloads/sg_postal_districts.kml", "sg_postal_districts")

# convert to same coordinate system as mrt
districts = spTransform(districts, mrt@proj4string)

districts_df <- data.frame(district = districts$Name, nbhds = districts$neighborhoods)

counts_mrt_lrt <- table(over(mrt, districts)$Name)

# defaults to 0 (will be missing from counts if there are no matches)
districts_df$n_mrt_lrt_stations = 0L
districts_df[
  match(names(counts_mrt_lrt), districts_df$district),
  "n_mrt_lrt_stations"] = as.integer(counts_mrt_lrt)

counts_mrt <- table(over(mrt[mrt$TYPE == "MRT", ], districts)$Name)

districts_df$n_mrt_stations = 0L
districts_df[
  match(names(counts_mrt), districts_df$district),
  "n_mrt_stations"] = as.integer(counts_mrt)

write.csv(
  districts_df,
  '~/n_mrt_stations_by_district.csv'
)