Making a Beautiful Map of Spain in ggplot2

A few weeks ago I read an article in which Timo Grossenbacher showed how he managed to plot, in my opinion, one of the most beautiful maps I have ever seen.

So I went and tried to replicate it.

First of all, here is the map.

mapa

As usual, you can download the code & data included in this post in github. I pushed some earlier versions of the map as well, with different color breaks so you can see the impact that binning has in data visualization.

The code.

First we import all the required libraries

setwd("/YOUR WORK DIR HERE/")

if (!require(rgdal)) {  
    install.packages("rgdal", repos = "http://cran.us.r-project.org")
    require(rgdal)
  }

  if (!require(rgeos)) {
    install.packages("rgeos", repos = "http://cran.us.r-project.org")
    require(rgeos)
  }
  if (!require(rgdal)) {
    install.packages("rgdal", repos = "http://cran.us.r-project.org")
    require(rgdal)
  }
  if (!require(raster)) {
    install.packages("raster", repos = "http://cran.us.r-project.org")
    require(raster)
  }
  if(!require(ggplot2)) {
    install.packages("ggplot2", repos="http://cloud.r-project.org")
    require(ggplot2)
  }
  if(!require(viridis)) {
    install.packages("viridis", repos="http://cloud.r-project.org")
    require(viridis)
  }
  if(!require(dplyr)) {
    install.packages("dplyr", repos = "https://cloud.r-project.org/")
    require(dplyr)
  }
  if(!require(gtable)) {
    install.packages("gtable", repos = "https://cloud.r-project.org/")
    require(gtable)
  }
  if(!require(grid)) {
    install.packages("grid", repos = "https://cloud.r-project.org/")
    require(grid)
  }
  if(!require(tidyr)) {
    install.packages("tidyr", repos = "https://cloud.r-project.org/")
    require(tidyr)
  }
}

Then we load the data. I found a shapefile containing Spanish municipalities in ArcGis, with no attribution provided.

To obtain Spain's census data, I used the wonderful data extraction tool provided by the Spanish National Statistics Institute. The tool is a nightmare to use, so if you want the data just go ahead and get it from my repo.

data_spain <- read.csv("Censuses2011_2.csv", stringsAsFactors = F)  
data_spain$municipality_code <- as.numeric(separate(data_spain, Municipality.of.residence, "municipality_code", " ")$municipality_code)  
data_spain$People <- as.numeric(data_spain$People)  
data_spain$Average.age <- as.numeric(data_spain$Average.age)

#We load the shapefile and convert it into a dataframe
municipalities_spain <- readOGR("Municipios_ETRS89_30N/Municipios_ETRS89_30N.shp", layer="Municipios_ETRS89_30N")  
map_data_fortified_spain <- fortify(municipalities_spain, region = "Codigo") %>% mutate(id = as.numeric(id))

#now we join the census data with the geometric data on the municipality_code
map_data_spain <- map_data_fortified_spain %>% left_join(data_spain, by = c("id" = "municipality_code"))   %>% fill(Average.age)  
rm(data_spain)  
rm(map_data_fortified_spain)  
rm(municipalities_spain)  

And finally, the plotting code.

pretty_breaks <- c(40,44,48,52,56)

# find the extremes
minVal <- min(map_data_spain$Average.age, na.rm = T)  
maxVal <- max(map_data_spain$Average.age, na.rm = T)  
# compute labels
labels <- c()  
brks <- c(minVal, pretty_breaks, maxVal)  
# round the labels (actually, only the extremes)
for(idx in 1:length(brks)){  
  labels <- c(labels,round(brks[idx + 1], 2))
}

labels <- labels[1:length(labels)-1]  
# define a new variable on the data with the breaks
map_data_spain$brks <- cut(map_data_spain$Average.age,  
                          breaks = brks, 
                          include.lowest = TRUE, 
                          labels = labels)

brks_scale <- levels(map_data_spain$brks)  
labels_scale <- rev(brks_scale)


theme_map <- function(...) {  
  theme_minimal() +
    theme(
      text = element_text(family = "Ubuntu Regular", color = "#22211d"),
      axis.line = element_blank(),
      axis.text.x = element_blank(),
      axis.text.y = element_blank(),
      axis.ticks = element_blank(),
      axis.title.x = element_blank(),
      axis.title.y = element_blank(),
      # panel.grid.minor = element_line(color = "#ebebe5", size = 0.2),
      panel.grid.major = element_line(color = "#ebebe5", size = 0.2),
      panel.grid.minor = element_blank(),
      plot.background = element_rect(fill = "#f5f5f2", color = NA), 
      panel.background = element_rect(fill = "#f5f5f2", color = NA), 
      legend.background = element_rect(fill = "#f5f5f2", color = NA),
      panel.border = element_blank(),
      ...
    )
}

#crazy function just to extend the legend extremes
extendLegendWithExtremes <- function(p){  
  p_grob <- ggplotGrob(p)
  legend <- gtable_filter(p_grob, "guide-box")
  legend_grobs <- legend$grobs[[1]]$grobs[[1]]
  # grab the first key of legend
  legend_first_key <- gtable_filter(legend_grobs, "key-3-1-1")
  legend_first_key$widths <- unit(2, units = "cm")
  # modify its width and x properties to make it longer
  legend_first_key$grobs[[1]]$width <- unit(2, units = "cm")
  legend_first_key$grobs[[1]]$x <- unit(0.15, units = "cm")

  # last key of legend
  legend_last_key <- gtable_filter(legend_grobs, "key-3-6-1")
  legend_last_key$widths <- unit(2, units = "cm")
  # analogous
  legend_last_key$grobs[[1]]$width <- unit(2, units = "cm")
  legend_last_key$grobs[[1]]$x <- unit(1.02, units = "cm")

  # grab the last label so we can also shift its position
  legend_last_label <- gtable_filter(legend_grobs, "label-5-6")
  legend_last_label$grobs[[1]]$x <- unit(2, units = "cm")

  # Insert new color legend back into the combined legend
  legend_grobs$grobs[legend_grobs$layout$name == "key-3-1-1"][[1]] <- 
    legend_first_key$grobs[[1]]
  legend_grobs$grobs[legend_grobs$layout$name == "key-3-6-1"][[1]] <- 
    legend_last_key$grobs[[1]]
  legend_grobs$grobs[legend_grobs$layout$name == "label-5-6"][[1]] <- 
    legend_last_label$grobs[[1]]

  # finally, I need to create a new label for the minimum value 
  new_first_label <- legend_last_label$grobs[[1]]
  new_first_label$label <- round(min(map_data_spain$avg_age_15, na.rm = T), 2)
  new_first_label$x <- unit(-0.15, units = "cm")
  new_first_label$hjust <- 1

  legend_grobs <- gtable_add_grob(legend_grobs, 
                                  new_first_label, 
                                  t = 6, 
                                  l = 2, 
                                  name = "label-5-0", 
                                  clip = "off")
  legend$grobs[[1]]$grobs[1][[1]] <- legend_grobs
  p_grob$grobs[p_grob$layout$name == "guide-box"][[1]] <- legend

  # the plot is now drawn using this grid function
  grid.newpage()
  grid.draw(p_grob)
}

p <- ggplot() +  
  geom_polygon(data = map_data_spain, aes(fill = brks, 
                                         x = long, 
                                         y = lat, 
                                         group = group)) +
  # municipality outline
  geom_path(data = map_data_spain, aes(x = long, 
                                      y = lat, 
                                      group = group), 
            color = "white", size = 0.1) +
  coord_equal() +
  theme_map() +
  theme(
    legend.position = c(0.7, 0.03),
    legend.text.align = 0,
    legend.background = element_rect(fill = alpha('white', 0.0)),
    legend.text = element_text(size = 14, hjust = 0, color = "#4e4d47"),
    legend.title = element_text(size = 20),
    plot.title = element_text(size = 28, hjust = 0.8, color = "#4e4d47"),
    plot.subtitle = element_text(size = 20, hjust = 0.8, face = "italic", color = "#4e4d47"),
    plot.caption = element_text(size = 14, hjust = 0.95, color = "#4e4d47"),
    plot.margin = unit(c(.5,.5,.2,.5), "cm"),
    panel.border = element_blank()
  ) +
  labs(x = NULL, 
       y = NULL, 
       title = "Spain's regional demographics", 
       subtitle = "Average age in Spanish municipalities, 2011", 
       caption = "Author: Manuel Garrido (@manugarri) Original Idea: Timo Grossenbacher (@grssnbchr), Geometries: ArcGis Data: INE, 2011;") + 
  scale_fill_manual(
    values = rev(magma(8, alpha = 0.8)[2:7]),
    breaks = rev(brks_scale),
    name = "Average age",
    drop = FALSE,
    labels = labels_scale,
    guide = guide_legend(
      direction = "horizontal",
      keyheight = unit(2, units = "mm"),
      keywidth = unit(70/length(labels), units = "mm"),
      title.position = 'top',
      title.hjust = 0.5,
      label.hjust = 1,
      nrow = 1,
      byrow = T,
      reverse = T,
      label.position = "bottom"
    )
  )
extendLegendWithExtremes(p)  

The code above is carefully designed to export the map as an image with a witdh of 2400 px.

Because Spain's Canary Islands are so far from the main Spanish Peninsula, a common practice in Spanish map making is to "move" the Canary Islands closer to mainland Spain. I did this in Gimp.

Notes.

  • I knew that Spain had a population problem, but damn!. The north west of the country looks like a big retirement home. The original Switzerland map had scale breaks at the 40-52 age range, but I had to expand it to 40-56- because of Spain's aging population.

  • Once again, I realize how sad the state of Open Data is in Spain.

    First, the Spanish National Statistic's data retrieval tool looks like something from the 90s (both in useability and performance).

    Second, the Spanish Population Census information is updated every 10 years. That means that the map is showing the most recent official data regarding Spain's population - at it is from 2011! This data should be updated more frequently.

    Third, if you go to the original map creator's site, you will see that his map has a beatiful topological layer on top of the municipalities. He uses a 1:1,000,000 scale raster file with topographic information provided by the Swiss Federal Office of Topography.

    I spent one day looking for something similar for Spain. It turns out that the Spanish Geographic Information Center only provides raster topological maps in 25 meters and 50 meters resolution, which means downloading hundreds of files and joining them. I didn't really want to do that just to play with some code.

    In the end, I made my own shaded relief raster from tiles taken from this super cool site, and a lot of Gimp processing. I did not include it in the map because that would mean removing municipalities (as Spain isn't as mountainous as Switzerland).

  • Even though the amount of effort poured into this map is impressive (one of the reasons I wanted to replicate it), I think that there should be another way of doing style customization in ggplot. The current code only works with a specific resolution in mind, and it requires a lot of trial and error until you find the right font sizes, alignments and such. Maybe using more relative terms, (ems for example) would make creating beautiful plots much easier.

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