由网友(月亮供电不足)分享简介：使用 plotly 的 subplots() 时如何删除图例中的重复项?How can I remove the duplicates in my legend when using plotly's subplots()? 这是我的 MWE:library(plotly)library(ggplot2)l...

使用 plotly 的 subplots() 时如何删除图例中的重复项?

How can I remove the duplicates in my legend when using plotly's subplots()?

这是我的 MWE:

library(plotly)
library(ggplot2)
library(tidyr)

mpg %>%
  group_by(class) %>%
  do(p = plot_ly(., x = ~cyl, y = ~displ, color = ~trans, type = 'bar')) %>%
  subplot(nrows = 2, shareX = TRUE, titleX = TRUE) %>%
  layout(barmode = 'stack')

推荐答案

使用 tidyverse 的另一种解决方法.在原来的 MWE 中增加了以下步骤:

Another workaround using the tidyverse. The following steps are added to the original MWE:

将 trans 列转换为因子.使用 tidyr 的 complete 填充每个 class 组中缺失因子级别的(非 NA)虚拟值.按照 MM 的建议将 showlegend 设置为 TRUE 用于单个组，将 legendgroup 设置为 trans 以进行链接子图之间的图例条目. Convert the trans column to a factor. Use tidyr's complete to fill (non-NA) dummy values for the missing factor levels in each class group. Follow M-M's suggestion setting showlegend to TRUE for a single group and legendgroup to trans to link the legend entries between subplots.

library(plotly)
library(tidyverse)

mpg %>%
    mutate_at("trans", as.factor) %>%  
    group_by(class) %>%
    group_map(.f = ~{          
          ## fill missing levels w/ displ = 0, cyl = first available value 
          complete(.x, trans, fill = list(displ = 0, cyl = head(.x$cyl, 1))) %>%
          plot_ly(x = ~cyl, y = ~displ, color = ~trans, colors = "Paired", type = "bar",
              showlegend = (.y == "2seater"), legendgroup = ~trans) %>%
          layout(yaxis = list(title = as.character(.y)), barmode = "stack")
        }) %>%
    subplot(nrows = 2, shareX = TRUE, titleY = TRUE)