如何在R语言的Plotly中按组调整标记点的边框颜色？

问题核心：使用Plotly时，试图用colour列指定标记点边框色，但Plotly未直接使用列中的颜色字符串，而是将其当作分类变量重新映射颜色。

原因 #

marker = list(line = list(color = ~colour))中的公式语法~colour会让Plotly将colour列视为分类变量，自动分配默认调色板中的颜色，而非直接使用列内的颜色字符串值。

解决方案 #

直接传递颜色向量而非使用公式语法，同时确保填充色的分组映射正确：

library(data.table)
library(plotly)

dt <- data.table(
  x = c(1,2,3,4,5),
  y = c(2,1,3,5,4),
  x2 = c(6,7,8,9,10),
  y2 = c(7,6,8,10,9),
  group = c("A","B","A","B","A"),
  group2 = c("X","Y","Z","X","Y"),
  colour = c("red","yellow","green","red","yellow")
)
group_colours <- setNames(c("orange","purple"), c("A","B"))

plot_ly(dt,
        x = ~x,
        y = ~y,
        type = "scatter",
        color = ~group,
        colors = group_colours,
        mode = "markers",
        marker = list(size = 15,
                      line = list(color = dt$colour,
                                  width = 2)),
        text = ~paste('</br> Group2:',group2,
                      '</br> Colour:', colour),
        height = 800) %>%
  add_markers(x = ~x2,
              y = ~y2,
              color = ~group,
              colors = group_colours,
              marker = list(size = 15,
                            line = list(color = dt$colour,
                                        width = 2)))

关键修改点 #

• 填充色映射：将colors = ~group_colours改为colors = group_colours，直接传递命名向量，确保分组与填充色正确对应。
• 边框色设置：将marker$line$color = ~colour改为marker$line$color = dt$colour，直接使用colour列的颜色字符串，避免Plotly自动映射。
• 新增点的设置：在add_markers中重复指定color = ~group和colors = group_colours，保证新增点的填充色与第一组保持一致。

内容的提问来源于stack exchange，提问作者isaacm1994