ggplot2：scale_fill_brewer中NA的图例

Question

我想知道如何在NA中获取scale_fill_brewer值的图例类别。这是我的MWE。

set.seed(12345)
dat <- 
  data.frame(
    Row = rep(x = LETTERS[1:5], times = 10)
    , Col = rep(x = LETTERS[1:10], each = 5)
    , Y = c(rnorm(n = 48, mean = 500, sd = 1), NA, NA)
  )

dat$Y1 <-  addNA(cut(log(dat$Y), 5))

levels(dat$Y1)
[1] "(6.21,6.212]"  "(6.212,6.214]" "(6.214,6.216]" "(6.216,6.218]" "(6.218,6.22]"  NA   


library(ggplot2)

ggplot(data =  dat, aes(x = Row, y = Col)) + 
  geom_tile(aes(fill = Y1), colour = "white") +
  scale_fill_brewer(palette = "PRGn")

Answer 1

您可以明确将缺失的值视为Y1因素的另一个级别，以便将其添加到您的图例中。

像以前一样切割变量后，您需要将NA添加到因子的级别。在这里，我将其添加为最后一级。

dat$Y1 <-  cut(log(dat$Y), 5)
levels(dat$Y1) <- c(levels(dat$Y1), "NA")

然后将所有缺失值更改为字符串NA。

dat$Y1[is.na(dat$Y1)] <- "NA"

这会使你的情节中的NA部分成为传奇：

Answer 2

我在没有更改原始数据框的情况下找到了变通方法，根据此post添加了额外的图例：

ggplot(data =  dat, aes(x = Row, y = Col)) + 
   geom_tile(aes(fill = Y1), colour = "white") +
   scale_fill_brewer(palette = "PRGn")+
   geom_point(data = dat, aes(size="NA"), shape =NA, colour = "grey95")+
   guides(size=guide_legend("NA", override.aes=list(shape=15, size = 10)))

为NA着色：

ggplot(data =  dat, aes(x = Row, y = Col)) + 
   geom_tile(aes(fill = Y1), colour = "white") +
   scale_fill_brewer(palette = "PRGn", na.value="red")+
   geom_point(data = dat, aes(size="NA"), shape =NA, colour = "red")+
   guides(size=guide_legend("NA", override.aes=list(shape=15, size = 10)))