通过 gganimate 制作动画条形图：view_follow 和 coord_flip 的冲突

我想创建一个动画条形图gganim包裹。条形图的坐标应通过翻转coord_flip（即水平条）和 x 轴应根据条的长度通过view_follow.

考虑以下示例数据：

# Create example data
df <- data.frame(ordering = c(rep(1:3, 2), 3:1, rep(1:3, 2)),
                 year = factor(sort(rep(2001:2005, 3))),
                 value = round(runif(15, 0, 100)),
                 group = rep(letters[1:3], 5))

如果我创建一个动画条形图而不coord_flip，一切正常：

library("gganimate")
library("ggplot2")

# Create animated ggplot without coord_flip
ggp <- ggplot(df, aes(x = ordering, y = value)) +
  geom_bar(stat = "identity", aes(fill = group)) +
  transition_states(year, transition_length = 2, state_length = 0) +
  view_follow(fixed_x = TRUE) # +
  # coord_flip()
ggp

但是，如果我添加coord_flip，轴无缘无故地从一侧移动到另一侧：

# Create animated ggplot with coord_flip
ggp2 <- ggplot(df, aes(x = ordering, y = value)) +
  geom_bar(stat = "identity", aes(fill = group)) +
  transition_states(year, transition_length = 2, state_length = 0) +
  view_follow(fixed_x = TRUE) +
  coord_flip()
ggp2

问题：如何翻转条形图的轴并启用灵活轴？

您可能需要考虑geom_barh来自 ggstance 包，而不是geom_bar + coord_flip:

library(ggstance)

ggplot(df, aes(y = ordering, x = value)) +
  geom_barh(stat = "identity", aes(fill = group)) +
  transition_states(year, transition_length = 2, state_length = 0) +
  view_follow(fixed_y = TRUE)