week3-map.org

JOM299

week 3: map of LGBTI index

Getting data

library(readr)
library(tidyverse)
library(dplyr)
rainbow_index <- read_csv("data/exportmap.csv") %>%
  select(Country, Score)
  
  Country    Score
  <chr>      <dbl>
1 Albania       33
2 Andorra       35
3 Armenia        7
4 Austria       56

What does our data look like?

rainbow_index %>% summary()

   Country              Score      
 Length:53          Min.   : 5.00  
 Class :character   1st Qu.:21.00  
 Mode  :character   Median :34.00  
                    Mean   :39.29  
                    3rd Qu.:56.75  
                    Max.   :91.00  
                    NA's   :5     

library(ggplot2)
rainbow_index %>% ggplot(aes(Score)) +
  geom_histogram(binwidth = 3)

A simple map of the world

getMap

Very simple solution to download and map country borders

library(rworldmap)
plot(getMap())

getMap and ggplot

getMap give us loads of informations about countries: their names, abbreviations, the continent they’re on, their population and GDP estimates, etc.

We use ggplot here to be able to compose our layers: getMap is our base map

library(sf)
worldMap <- getMap(resolution = "low")
worldMap <- st_as_sf(worldMap)

ggplot(worldMap) + geom_sf()

Merging our index score and the map data

Our task is to find a way to merge our two datasets. We remember this helpful cheatsheet:

https://camo.githubusercontent.com/c8c1f1bda76407340ae37fa210c38cac480016bb/68747470733a2f2f6d696b6f6f6e747a2e6769746875622e696f2f646174612d63617270656e7472792d7765656b2f696d672f64706c79722d6a6f696e732e706e67

Finding the common property

And it seems that the SOVEREIGNT column of our map contains full country names:

library(sf)
worldMap <- getMap(resolution = "high")
worldMap$SOVEREIGNT %>% head()

[1] Netherlands    Afghanistan    Angola         United Kingdom Albania        Finland       
204 Levels: Afghanistan Albania Algeria Andorra Angola Antarctica ... Zimbabwe

Final merge

We can merge with our rainbow_index$Country.

# get the map again!!!
worldMap <- getMap(resolution = "low")
worldMap@data <- left_join(worldMap@data, rainbow_index, 
                    by = c("SOVEREIGNT" = "Country"))
worldMap <- st_as_sf(worldMap)

Basics of mapping

Simple map

Technically, this is a map of our data…

worldMap %>%
  ggplot() +
  geom_sf(aes(fill = Score))

Let’s zoom in

We zoom in by specifying latitude and longitude minimum and maximums to coord_sf

Let’s zoom in

worldMap %>%
  ggplot() +
  geom_sf(aes(fill = Score)) +
  coord_sf(xlim = c(-10, 50), ylim = c(30, 75), expand = FALSE)

Filter missing data

worldMap %>% filter(!is.na(Score)) %>%
  ggplot() + 
  geom_sf(aes(fill = Score)) +
  coord_sf(xlim = c(-10, 50), ylim = c(30, 75), expand = FALSE)

Better colours

Excellent Datawrapper guide on colours

One important tool among other is ColorBrewer.

From there we can grab colours we like and feed them like so:

scale_fill_gradient(low, high)

In action

library(RColorBrewer)
worldMap %>% filter(!is.na(Score)) %>%
  ggplot() + 
  geom_sf(aes(fill = Score,
    colour = I("gray80")), size = 1/100) +
  coord_sf(xlim = c(-10, 50), ylim = c(30, 75), expand = FALSE) +
  scale_fill_gradient(low = I("#d7191c"), high = I("#1a9641")) + 
  theme_minimal()

Er, actual better colours

theme_opts<-list(theme(panel.grid.minor = element_blank(),
                         panel.grid.major = element_line(colour = "transparent"),
                         panel.background = element_blank(),
                         plot.background = element_blank(),
                         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(),
                         legend.position = "right"))

Bis

worldMap %>% filter(!is.na(Score)) %>%
    ggplot() + 
    geom_sf(aes(fill = Score, colour = I("gray80")), size = 1/100) +
    coord_sf(xlim = c(-10, 50), ylim = c(30, 75), expand = FALSE) +
    scale_fill_distiller(type = "div", palette = "RdYlGn", direction = 1) +
    theme_minimal() + theme_opts +
    ggtitle("LGBT rights in eastern and western Europe")