根据具体因素规定相同的颜色图

Question

我在ggplot2中遇到颜色映射方面的困难。四个地块中有两个具有相同的六个县变量。然而，＆＃34;一氧化碳＆＃34;和＆＃34;粗颗粒物＆＃34;次要情节只有五个（皮尔斯县失踪）。

每种污染物在y轴上具有不同的单位，并且在单个ggplot中标记单个面是一个挑战。为了解决这个问题，我将逐个生成每个绘图，然后使用gridExtra将它们组合在一起。

是否可以将六个县的三个地块的相同颜色映射应用于一氧化碳图？

以下是我如何制作个人情节的示例：

library(ggplot2)
library(dplyr)
library(gridExtra)


p1 <- ggplot(filter(df, pollutant == "Nitrogen dioxide"), aes(x = as.factor(season), y = value, fill = as.factor(county))) + 
    geom_boxplot(position = "dodge")

    ## I'm excluding a bunch of code to format the font and size of the title/legend/axis labels


g <- grid.extra(p1, p2, p3, p4)

Answer 1

感谢评论的一些帮助，我设法产生了预期的结果。这比我想象的容易得多。 hue_pal()函数将来肯定会对我有用。谢谢你们！

library(scales)

## determine what the default color palette is for ggplot2 with 6 factor levels:
hue_pal()(6)
#[1] "#F8766D" "#B79F00" "#00BA38" "#00BFC4" "#619CFF" "#F564E3"

## next we need to create a custom color palette using these six colors:
cols <- c("Ada" = "#F8766D", "Bernalillo" = "#B79F00",
          "Multnomah" = "#00BA38", "Pierce" = "#00BFC4",
          "Sacramento" = "#619CFF", "Salt Lake" = "#F564E3")

## I'm mapping each color to the specific factor level (County Name)
## This ensures that each county maintains the same color throughout each plot
## regardless if there are 5 or 6 factor levels!

p1 <- ggplot(filter(df, pollutant == "Nitrogen dioxide"),
             aes(x = as.factor(season),
                 y = value,
                 fill = as.factor(county))) + 
      geom_boxplot(position = "dodge") + 

      ## here's where we'll add our custom color palette:
      scale_fill_manual(values = cols)

p1