Mapping data using R and leaflet

By nsaunders

(This article was first published on R – What You’re Doing Is Rather Desperate, and kindly contributed to R-bloggers)

The R language provides many different tools for creating maps and adding data to them. I’ve been using the leaflet package at work recently, so I thought I’d provide a short example here.

Whilst searching for some data that might make a nice map, I came across this article at ABC News. It includes a table containing Australian members of parliament, their electorate and their voting intention regarding legalisation of same-sex marriage. Since I reside in New South Wales, let’s map the data for electorates in that state.

Here’s the code at Github. The procedure is pretty straightforward:

  • Obtain a shapefile of New South Wales electorates (from here) and read into R
  • Read the data from the ABC News web page into a data frame (very easy using rvest)
  • Match the electorate names from the two sources (they match perfectly, well done ABC!)
  • Use the match to add a voting intention variable to the shapefile data
  • Use leaflet to generate the map of New South Wales with electorates coloured by voting intention

At right, a non-interactive screen grab of the result (click for larger version). For the full interactive map visit this RPubs page where you can zoom, drag and mouse-over to see how Leaflet maps work.

I like R/leaflet a lot. It generates high-quality interactive maps and it’s easy to experiment in and publish from Rstudio. Some of the syntax feels a little clunky (a mix of newer “pipes” and older “formula-style”) and generating colour palettes feels strange if you spend most time in ggplot2. However, some of that is probably my inexperience with the package as much as anything else.

Filed under: australia, australian news, R, statistics Tagged: leaflet, maps, politics, ssm

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