coords.csv

mapit-example.R

# A simple example of taking coordinates from a CSV file and looking
# up areas around those points in MapIt.  This assumes that you're
# looking for the 'OLG' type in MapIt and that your coordinates are in
# WGS 84 - change the 'srid' and 'mapit.type' variable if that isn't
# right.  This just prints out the results.

library(RCurl)
library(rjson)

coords <- read.csv('coords.csv')

srid <- "4326"
# OLG is Lower Layer Super Output Area, Generalised
mapit.type <- "OLG"

find_areas <- function(coord) {
  lon <- coord[1]
  lat <- coord[2]
  coord.string <- paste(lon, ',', lat, sep="")
  
  url <- paste("http://mapit.mysociety.org/point/",
               srid,
               "/",
               coord.string,
               '.json?type=',
               mapit.type,
               sep="")
  
  results <- fromJSON(getURL(url))
  # Sleep for just over a second to avoid hitting the MapIt rate
  # limiting:
  Sys.sleep(1.1)
  
  if (length(results) == 0) {
    print(paste("No", mapit.type, "found around", coord.string))
  } else {
    for (area.id in names(results)) {
      result <- results[[area.id]]
      print(paste(coord.string,
                  " is in ",
                  result$name,
                  " (ONS: ", result$codes$ons, ")",
                  sep=""))
    }
  }
}

apply(coords, 1, find_areas)