Plotting bars on a map with ggplot

Question

I want to plot a single bar per country onto a map.

My code:

library(tidyverse)
library(rworldmap)

# Get map data
worldMap <- map_data("world")

# Select only some countries and add values
europe <- data.frame("country"=c("Austria", "Belgium", "Germany", "Spain", "Finland", "France", 
                                 "Greece", "Ireland", "Italy", "Netherlands", "Portugal",
                                 "Bulgaria","Croatia","Cyprus", "Czech Republic","Denmark","Estonia", "Hungary",
                                 "Latvia", "Lithuania","Luxembourg","Malta", "Poland", "Romania","Slovakia",
                                 "Slovenia","Sweden","UK", "Switzerland",
                                 "Ukraine", "Turkey", "Macedonia", "Norway", "Slovakia", "Serbia", "Montenegro",
                                 "Moldova", "Kosovo", "Georgia", "Bosnia and Herzegovina", "Belarus", 
                                 "Armenia", "Albania", "Russia"),
                     "Growth"=c(1.0, 0.5, 0.7, 5.2, 5.9, 2.1, 
                                       1.4, 0.7, 5.9, 1.5, 2.2, rep(NA, 33)))

# Merge data and keep only Europe map data
worldMap$value <- europe$Growth[match(worldMap$region,europe$country)]

worldMap <- worldMap %>%
  filter(region %in% europe$country) 

# Plot it 
P <- ggplot()+ 
  geom_polygon(data = worldMap, aes(x=long, y = lat, group = group, fill=value),
               colour = "white", size = 0.1)+
  coord_map(xlim = c(-13, 35),  ylim = c(32, 71))

I am aware of this solution but I fail to replicate it:

# Adding Centroids
centres <- worldMap %>%
  group_by(region) %>%
  summarize(long=mean(long, na.rm = T), 
            lat=mean(lat, na.rm = T))

centres$value <- europe$Growth[match(centres$region,europe$country)]

# Trying to add the barplots
europe$id <- (rep(1:length(europe$country)))

bar.testplot_list <- 
  lapply(1:length(europe$country), function(i) { 
    gt_plot <- ggplotGrob(
      ggplot(europe[europe$id == i,])+
        geom_bar(aes(factor(id),Growth,group=country), fill = rainbow(length(europe$country))[i],
                 position='dodge',stat='identity', color = "black") +
        labs(x = NULL, y = NULL) + 
        theme(legend.position = "none", rect = element_blank(),
              line = element_blank(), text = element_blank()) 
    )
    panel_coords <- gt_plot$layout[gt_plot$layout$name == "panel",]
    gt_plot[panel_coords$t:panel_coords$b, panel_coords$l:panel_coords$r]
  })

bar_annotation_list <- lapply(1:length(europe$country), function(i) 
  annotation_custom(bar.testplot_list[[i]], 
                    xmin = centres$long[centres$region == as.character(europe$country[i])] - 5e3,
                    xmax = centres$long[centres$region == as.character(europe$country[i])] + 5e3,
                    ymin = centres$lat[centres$region == as.character(europe$country[i])] - 5e3,
                    ymax = centres$lat[centres$region == as.character(europe$country[i])] + 5e3) )

result_plot <- Reduce(`+`, bar_annotation_list, P)
result_plot

I also see that it does not work with coord_map but the result is equally not working when I do not include coord_map(xlim = c(-13, 35), ylim = c(32, 71)). --> Could somebody explain how I can add the growth variable as a bar on every respective country?

Why are the answers posted in the questions you linked to not working? — erc, Jan 16 '19 at 15:24
sorry - I should have been more specific. Unfortunately, I cannot replicate the solutions provided by them because I do not understand them. I do understand that there should be a solution in there but I do not understand how it works — BeSeLuFri, Jan 16 '19 at 15:42
Possible duplicate of [How to plot barchart onto ggplot2 map](https://stackoverflow.com/questions/36063043/how-to-plot-barchart-onto-ggplot2-map) — erc, Jan 17 '19 at 07:58
You should be more specific then in your question and show how far you got (I think you pretty much need to follow the answer in the first question you linked to) and where you got stuck. — erc, Jan 17 '19 at 08:00
My main problem with [How to plot brchart onto ggplot2 map](https://stackoverflow.com/questions/36063043/how-to-plot-barchart-onto-ggplot2-map) is that I cannot replicate it from the start because the data have changed. Most likely it is a stupid question and I am making an easy mistake but I never plotted stuff before — BeSeLuFri, Jan 17 '19 at 09:02

score 1 · Accepted Answer · answered Jan 17 '19 at 16:13

This should be a working solution. Note that the overseas territories are biasing the France centroid away from the mainland France centroid.

library(tidyverse)
#library(rworldmap)
library(sf)
# Data 
library(spData)      
library(spDataLarge)

# Get map data
worldMap <- map_data("world")

# Select only some countries and add values
europe <- 
  data.frame("country"=c("Austria",
                         "Belgium", 
                         "Germany",
                         "Spain", 
                         "Finland", 
                         "France", 
                         "Greece", 
                         "Ireland", 
                         "Italy", 
                         "Netherlands", 
                         "Portugal",
                                 "Bulgaria","Croatia","Cyprus", "Czech Republic","Denmark","Estonia", "Hungary",
                                 "Latvia", "Lithuania","Luxembourg","Malta", "Poland", "Romania","Slovakia",
                                 "Slovenia","Sweden","UK", "Switzerland",
                                 "Ukraine", "Turkey", "Macedonia", "Norway", "Slovakia", "Serbia", "Montenegro",
                                 "Moldova", "Kosovo", "Georgia", "Bosnia and Herzegovina", "Belarus", 
                                 "Armenia", "Albania", "Russia"),
                     "Growth"=c(1.0, 0.5, 0.7, 5.2, 5.9, 2.1, 
                                1.4, 0.7, 5.9, 1.5, 2.2, rep(NA, 33)))

# Merge data and keep only Europe map data

data("world")

worldMap <- world

worldMap$value <- europe$Growth[match(worldMap$region,europe$country)]

centres <- 
  worldMap %>%
  filter()
  st_centroid()

worldMap <- worldMap %>%
  filter(name_long %in% europe$country) 

# Plot it 

centroids <- 
  centres$geom %>% 
  purrr::map(.,.f = function(x){data.frame(long = x[1],lat = x[2])}) %>% 
  bind_rows %>% data.frame(name_long = centres$name_long) %>% 
  left_join(europe,by = c("name_long" = "country"))


barwidth = 1
barheight = 0.75

ggplot()+ 
  geom_sf(data = worldMap, color = "black",fill = "lightgrey",
               colour = "white", size = 0.1)+
  coord_sf(xlim = c(-13, 35),  ylim = c(32, 71)) + 
  geom_rect(data = centroids,
            aes(xmin = long - barwidth,
                xmax = long + barwidth,
                ymin = lat,
                ymax = lat + Growth*barheight)) + 
  geom_text(data = centroids %>% filter(!is.na(Growth)),
            aes(x = long,
                y = lat + 0.5*Growth*0.75,
                label = paste0(Growth," %")),
            size = 2) + 
  ggsave(file = "test.pdf",
         width = 10,
         height = 10)

Plotting bars on a map with ggplot

1 Answers1