用gganimate建立堆叠的直方图

Question

我试图显示随时间变化的直方图。可以从1952年的数据开始，然后每年更新直方图，然后不断增长。

这条路似乎很费力，我认为使用transition_reveal可以随着时间的推移缓慢地显示更多数据。这似乎不起作用。

假设我从这里开始：

library(gapminder)
library(tidyverse)
library(gganimate)

ggplot(gapminder, 
       aes(lifeExp, fill = fct_rev(factor(year)), group = fct_rev(factor(year)))) +
  geom_histogram(position = "stack", bins = 20) +
  transition_reveal(year)  

严重失败。

我可以和transition_layer一起消磨时间，就像这样：

ggplot(gapminder, aes(lifeExp, fill = fct_rev(factor(year)))) +
  geom_histogram(position = "stack", bins = 20, 
                 data = filter(gapminder, year<= 1952)) +
  geom_histogram(position = "stack", bins = 20, 
                 data = filter(gapminder, year<= 1957)) +
  geom_histogram(position = "stack", bins = 20, 
                 data = filter(gapminder, year<= 1962)) +
  geom_histogram(position = "stack", bins = 20, 
                 data = filter(gapminder, year<= 1967)) +
  geom_histogram(position = "stack", bins = 20, 
                 data = filter(gapminder, year<= 1972)) +
  geom_histogram(position = "stack", bins = 20, 
                 data = filter(gapminder, year<= 1977)) +
  transition_layers()  

产生期望的结果，但是不方便。有更便携的方法吗？

以下是我正在寻找的gif文件：

Answer 1

我无法使用geom_histogram来解决这个问题，但是我可以通过从geom_rect生成堆叠的直方图来实现。

bin_yrs = 2
a <- gapminder %>%
  count(year, life_bin = floor(lifeExp / bin_yrs) * bin_yrs) %>%
  complete(year, life_bin, fill = list(n = 0)) %>%
  arrange(year, life_bin) %>%
  group_by(life_bin) %>%
  mutate(dummy = lag(cumsum(n), default = 0)) %>%
  ungroup() %>%

  ggplot(aes(xmin = life_bin, 
             xmax = life_bin + bin_yrs,
             ymin = dummy, 
             ymax = dummy + n,
             fill = as.factor(year))) +
  geom_rect() +
  transition_manual(year) +
  shadow_trail()
animate(a, nframes = 12, fps = 4, width = 600, height = 300)