In martinjhnhadley/oidnChaRts: Utility Functions For htmlwidget Visualisations

Overview of function

geo_choropleth_chart can be used to create the following kinds of charts:

Geo choropleth charth

Geo choropleth charts contain geographic regions (i.e. countries) which are shaded/coloured according to a shared property of all regions (i.e. population). Choropleth are extrmely popular charts for comparing regions to one another, however they require significant effort to be put into curating the shapefiles that constitute the geographic regions.

## TO DO: Make an example

As with all oidnChaRts libraries, you are advised to load the htmlwidget library you're using directly.

data_world_shapefiles

library(oidnChaRts)

This vignette covers the use of geo choropleth charts for visualising data with a variety of htmlwidget libraries, for demonstration purposes we use a set of shapefiles from http://www.naturalearthdata.com/downloads/50m-cultural-vectors/. The shapesfiles have been pre-manipulated into a SpatialPolygonsDataFrame object ready for manipulation in R, here's a summary of the dataset:

summary(data_world_shapefiles)

Rather than plotting all of the countries of the world, let's restrict ourselves to Asia:

asia_shapefiles <- data_world_shapefiles %>%
  filter(continent == "Asia")

Colorscales

Before creating our choropleth we must consider the information communicated by the colour of the map regions, is the measure:

A categorical variable (i.e. Southern Asia, Western Asia, Central Asia)
A continuous variable (i.e. population of the region)

These two types of variable work best with different types of legend, our generic geo_choropleth_chart function must therefore

geo_choropleth_chart(
  spdf = ,
  library = ,
  region.border.width = ,
  region.border.color = ,
  region.value = ,
  legend = list(
    type = "continuous", # default 
    rcolorbrewer.palette = , # NULL if 
    minColor = NULL, # null if not 
  )
)