erasmus_map.R

# Original Idea and code by Jules Beley
# https://github.com/julesbeley/Erasmusmap/blob/master/Erasmus.R
# https://medium.com/@jules.beley/making-a-map-with-eu-data-on-r-erasmus-exchanges-by-country-3f5734dcd4ff

library(tidyverse)
library(maps)
library(countrycode)

download.file("http://data.europa.eu/euodp/data/uploads/EAC/SM_2012_13_20141103_01.csv", "erasmus.csv") # this may take a little while

erasmus <- read.csv("erasmus.csv", sep = ";")

# create counts of home institutions
home <- erasmus %>% 
  mutate(HOME_INSTITUTION_CTRY_CDE = ifelse(str_detect(HOME_INSTITUTION_CTRY_CDE, "BE"), "BE", as.character(HOME_INSTITUTION_CTRY_CDE))) %>% # combine Belgium
  count(HOME_INSTITUTION_CTRY_CDE)

# create counts of host institutions
host <- erasmus %>% 
  filter(HOST_INSTITUTION_COUNTRY_CDE != "???") %>% # remove unknowns
  mutate(HOST_INSTITUTION_COUNTRY_CDE = ifelse(str_detect(HOST_INSTITUTION_COUNTRY_CDE, "BE"), "BE", as.character(HOST_INSTITUTION_COUNTRY_CDE))) %>% # combine Belgium
  count(HOST_INSTITUTION_COUNTRY_CDE)

# fix the country code
countries <- countrycode(host$HOST_INSTITUTION_COUNTRY_CDE, "eurostat", "eurostat.name", custom_match = c(GR = 'Greece', DE = 'Germany', UK = 'UK'))

map_data("world") %>% # get world data
  left_join(data.frame(country = countries, ratio = host$n/home$n), by = c("region" = "country")) %>% # join with the host/home ratio
  ggplot(aes(x = long, y = lat, group = group, fill = ratio)) +
  geom_polygon() +
  coord_fixed(xlim = c(-9, 42.5), ylim = c(36, 70.1), ratio = 1.5) +
  scale_fill_viridis_c(option = "plasma", direction = -1) +
  theme_void() +
  theme(panel.background = element_rect(fill = "lightcyan1"))