You can create a choropleth of Countries with the function
library(choroplethr) ?df_pop_country data(df_pop_country) ?country_choropleth country_choropleth(df_pop_country)
As demonstrated above, the only required parameter to
country_choropleth is a data.frame. You can see the optional parameters by typing
This map demonstrates another feature of choroplethr: regions for which no value is provided (what is the population of Antarctica?) appear, by default, as black.
The data.frame that you provide to
country_choropleth must have one column named “region” and one column named “value”. Your entries for “region” must exactly match how regions are named in the map which choroplethr uses. These names are defined in the object
library(choroplethrMaps) ?country.regions data(country.regions) head(country.regions)
region iso2c 1 afghanistan AF 2 angola AO 3 azerbaijan AZ 4 moldova MD 5 madagascar MG 6 mexico MX
In order to use choroplethr, you must use the naming convention in the “region” column of country.regions. That is, you must use full names in all lowercase letters.
country_choropleth function provides two parameters to facilitate exploring data:
num_colors defaults to 7, which means that there are 7 colors on the map. An equal number of regions is assigned to each color; a value of 1 uses a continuous scale.
zoom defaults to NULL, which means that all states are shown. You can set it to be a vector of valid regions.
As an example, here is how you can use choroplethr to show the population of the US, Canada and Mexico.
country_choropleth(df_pop_country, title = "2012 Population Estimates", legend = "Population", num_colors = 1, zoom = c("united states of america", "mexico", "canada"))
Any customization outside the optional parameters presented above will require you to create a
CountryChoropleth object. choroplethr uses R6 to take advantage of object-oriented programming. Here is an example of using the
ggplot2_scale on the base Choropleth object to customize the palette used.
library(ggplot2) choro = CountryChoropleth$new(df_pop_country) choro$title = "2012 Population Estimates" choro$ggplot_scale = scale_fill_brewer(name="Population", palette=2) choro$render()