animated_pyramid.R

library(idbr) # devtools::install_github('walkerke/idbr')
library(ggplot2)
library(animation)
library(dplyr)
library(ggthemes)

idb_api_key("Put your Census API key here")

male <- idb1('CH', 2016:2050, sex = 'male') %>%
  mutate(POP = POP * -1,
         SEX = 'Male')

female <- idb1('CH', 2016:2050, sex = 'female') %>%
  mutate(SEX = 'Female')

china <- rbind(male, female) %>%
  mutate(abs_pop = abs(POP))

# Animate it with a for loop

saveGIF({

  for (i in 2016:2050) {
    
    title <- as.character(i)
    
    year_data <- filter(china, time == i)
    
    g1 <- ggplot(year_data, aes(x = AGE, y = POP, fill = SEX, width = 1)) +
      coord_fixed() + 
      coord_flip() +
      annotate('text', x = 98, y = 8000000, 
               label = 'Data source: US Census Bureau IDB via the idbr R package', size = 3.5) + 
      geom_bar(data = subset(year_data, SEX == "Female"), stat = "identity") +
      geom_bar(data = subset(year_data, SEX == "Male"), stat = "identity") +
      scale_y_continuous(breaks = seq(-10000000, 10000000, 5000000),
                         labels = paste0(as.character(c(seq(10, 0, -5), c(5, 10))), "m"), 
                         limits = c(min(china$POP), max(china$POP))) +
      theme_economist(base_size = 14) + 
      scale_fill_economist() + 
      ggtitle(paste0('Population structure of China, ', title)) + 
      ylab('Population') + 
      xlab('Age') + 
      theme(legend.position = "bottom") + 
      guides(fill = guide_legend(reverse = TRUE))

    print(g1)
    
  }

}, movie.name = 'china_pyramid.gif', interval = 0.1, ani.width = 700, ani.height = 600)