The dorling algorithm doesn't work on the entire country, because it is very clustered at the cities. To get a reasonable cartogram we need to extract out the cities, expand these with dorling independently. This function does the extraction.
Arguments
- aec_data
data with centroids of electoral divisions
- ctr
centroids of subset
- expand
how large a chunk to cut out
- ...
other arguments
Examples
library(dplyr)
library(ggplot2)
nat_map16 <- nat_map_download(2016)
nat_data16 <- nat_data_download(2016)
nat_data16 <- nat_data16 %>% select(-c(x,y)) # remove existing cartogram coordinates
adelaide <- aec_extract_f(nat_data16, ctr=c(138.6, -34.9), expand=c(2,3))
ggplot(data=nat_map16) +
geom_polygon(aes(x=long, y=lat, group=group, order=order),
fill="grey90", colour="white") +
geom_point(data=adelaide, aes(x=long_c, y=lat_c), size=2, alpha=0.4,
colour="#f0027f") +
xlim(c(136, 142)) + ylim(-36, -33) +
coord_equal()
#> Warning: Ignoring unknown aesthetics: order
