是否在ggplot geom_bar中更改NA值的标签和颜色？

library(ggplot2)

# 创建一个包含NA值的数据框
df <- data.frame(x = c("A", "B", NA, "C", "D"),
                 y = c(1, 2, 3, 4, 5))

# 绘制柱状图
ggplot(df, aes(x = x, y = y)) +
  geom_bar(stat = "identity") +
  scale_x_discrete(breaks = c(levels(df$x), NA),
                   labels = c(levels(df$x), "Missing"))

library(ggplot2)

# 创建一个包含NA值的数据框
df <- data.frame(x = c("A", "B", NA, "C", "D"),
                 y = c(1, 2, 3, 4, 5))

# 绘制柱状图
ggplot(df, aes(x = x, y = y, fill = x)) +
  geom_bar(stat = "identity") +
  scale_fill_manual(values = c("A" = "red", "B" = "blue", NA = "gray"))