使用 ggplotly() 时反转图例顺序

我想反转水平条形图图例的顺序。添加时guides(fill = guide_legend(reverse = TRUE)) to the ggplot它工作正常（参见第二个图）。然而申请后ggplotly()图例再次采用默认顺序。

如何颠倒顺序plotly legend without改变条形的顺序？

library(ggplot2)
library(dplyr)
data(mtcars)

p1 <- mtcars %>%
  count(cyl, am) %>%
  mutate(cyl = factor(cyl), am = factor(am)) %>%
  ggplot(aes(cyl, n, fill = am)) +
  geom_col(position = "dodge") +
  coord_flip()
p1

p2 <- p1 + guides(fill = guide_legend(reverse = TRUE))
p2

plotly::ggplotly(p2)

添加@Zac Garland 的精彩答案是一个适用于任意长度图例的解决方案：

library(ggplot2)
library(dplyr)

reverse_legend_labels <- function(plotly_plot) {
  n_labels <- length(plotly_plot$x$data)
  plotly_plot$x$data[1:n_labels] <- plotly_plot$x$data[n_labels:1]
  plotly_plot
}

p1 <- mtcars %>%
  count(cyl, am) %>%
  mutate(cyl = factor(cyl), am = factor(am)) %>%
  ggplot(aes(cyl, n, fill = am)) +
  geom_col(position = "dodge") +
  coord_flip()

p2 <- mtcars %>%
  count(am, cyl) %>%
  mutate(cyl = factor(cyl), am = factor(am)) %>%
  ggplot(aes(am, n, fill = cyl)) +
  geom_col(position = "dodge") +
  coord_flip()

p1 %>%
  plotly::ggplotly() %>%
  reverse_legend_labels()

p2 %>%
  plotly::ggplotly() %>%
  reverse_legend_labels()