Reverse the legend order when using ggplotly()

Question

I would like to reverse the order of the legend for a horizontal bar chart. When adding guides(fill = guide_legend(reverse = TRUE)) to the ggplot it works fine (see second plot). However, after applying ggplotly() the legend is again in the default order.

How to reverse the order of the plotly legend without changing the order of the bars?

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)

score 6 · Answer 1 · answered Jan 10 '20 at 11:34

Adding to the great answer of @Zac Garland here is a solution that works with legends of arbitrary length:

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()

Also, can you please add some explanation as to what the `reverse_legend_labels` function is doing? — Ed_Gravy, Aug 16 '22 at 13:49

score 3 · Accepted Answer · answered Jan 08 '20 at 15:41

When you call ggplotly, it's really just creating a list and a function call on that list.

So if you save that intermediate step, you can modify the list directly. and as such, modify the plot output.

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()

html_plot <- ggplotly(p1)

replace_1 <- html_plot[["x"]][["data"]][[2]]
replace_2 <- html_plot[["x"]][["data"]][[1]]
html_plot[["x"]][["data"]][[1]] <- replace_1
html_plot[["x"]][["data"]][[2]] <- replace_2

html_plot

plot output

score 1 · Answer 3 · answered Jan 06 '20 at 12:59

1

A simple solution is to define the order of the levels of the factor variable am:

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


df <-  mtcars %>%
  count(cyl, am) %>%
  mutate(cyl = factor(cyl), am = factor(as.character(am), levels = c("1", "0"))) 

head(df)


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

plotly::ggplotly(p1)

answered Jan 06 '20 at 12:59

Rami Krispin

79
1
6

Thanks @Rami Krispin! What I am trying to achieve though is that the color of the upper bar matches the color of the upper legend. Here this issue remains. The upper bar is green but the upper legend is orange. – Thomas Neitmann Jan 06 '20 at 13:05

Reverse the legend order when using ggplotly()

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