GeoTuple API access from R

example_getpoints.R

# Download JSON via GeoTuple API
# http://geotuple.org//pages/api.html

library(jsonlite)
library(httr)

# Thanks to http://stackoverflow.com/users/5729528/daeyoung-kim
# for this function
getFunctionEndPoint <- function(url, format) {
  return(paste(url, format, sep = '/'))
}

# set up http request:
#  CalEnviroScreen + Income per Capita 
#  for Sacramento downtown area
api_url <- "http://geotuple.com/ocpu/user/rolandhhansson/library/geotuple/R/api_getpoints"
API_KEY <- "YOUR API KEY"
args <- list(sw_lon=-121.552, sw_lat=38.543, ne_lon=-121.44, ne_lat=38.61, zoom=11, themes=list("calenviro", "inc_percap"), key=API_KEY)
# make request
resp <- POST(
  url = getFunctionEndPoint(
    url = api_url,
    format = "json"),
  body = args, 
  encode = 'json')
# into data frame
df <- fromJSON(rawToChar(resp$content))

# fit linear model and plot regression line
if (length(df) > 0) {
  frm <- formula(paste("calenviro","~","inc_percap"))
  LM.model = lm(frm, data=df)
  plot(frm, data=df, pch=20, xlab="Income per Capita", ylab="CalEnviroScreen")
  abline(LM.model, col="red")  # Draws the regression line on the plot
} else {
  print("Invalid request or quota exceeded!")  # max 1000 points per request and/or 5 < requests/minute
}