Load up NI shapefile

get_NI_population_map.R

library(magrittr)
library(ggplot2)
library(rgdal)


# Input `mapType` can either be "parliamentary" or "county"


getNIPopulationMap <- function(mapType = "parliamentary") {
  normaliseVector <- function(x) {
    normalisation <- (x-min(x))/(max(x)-min(x))
    return(normalisation * 100)
  }
  
  mapDataLocation <- paste0("NI-", mapType, "-boundaries")
  
  # Load NI shapefile into R
  NIShapefile <- rgdal::readOGR(
    dsn = getwd() %>% paste0(
      "/data/ODNI/maps/", mapType, "/", mapDataLocation, ".shp"),
    layer = mapDataLocation)
  
  # use the NAME_2 field to create data frame
  NIMap <- ggplot2::fortify(
    model = NIShapefile)
  
  # Create population data
  NIMap$count <- normaliseVector(rexp(
    n = NIMap %>% nrow(), 
    rate = 1))
  
  # Plot NI map
  mapPlot <- ggplot(
    data = NIMap, 
    aes(x = long, y = lat, 
        group = group, fill = count)) + 
    geom_polygon(
      colour = "white", 
      size = 0.5, 
      aes(group = group)) +
    scale_fill_gradient(
      low = "firebrick1", 
      high = "steelblue") + 
    ggtitle(
      "Projected population change, Northern Ireland, 2016-2041")  + 
    theme(
      axis.text = element_blank(),
      axis.ticks = element_blank(),
      panel.border = element_blank(),
      panel.background = element_blank(),
      panel.grid.major = element_blank(),
      panel.grid.minor = element_blank(),
      plot.title = element_text(
        family = "Arial"),
      legend.position = "none")
  
  # Save map
  ggsave(filename = getwd() %>% 
           paste0('/figures/raw/populationMap.png'),
         plot = mapPlot)
  
  return(mapPlot)
}