r - 如何在一个图例中结合 alpha 和颜色

Question

我有一个堆叠条形图，其中颜色代表类别，我调整了 alpha 以将它们分割为 2。
图例显示了 alpha(灰色阴影)和颜色。
但是我想制作一个包含组合的图例。

为了将它们结合起来，我查看了 this question但我不能结合阿尔法和填充。
这是一个不起作用的可重复数字:

mtcars %>% 
ggplot(aes(gear, mpg, fill = as.factor(vs), alpha = as.factor(am)))+
geom_bar(stat = "identity")+
scale_fill_manual(name = "legend",
                  values = c(
                      "0" = "red",
                      "1" = "blue",
                      "0"="red",
                      "1"="blue"
                      ),
                  labels = c("V-engine, automatic", 
                             "V-engine, manual",
                             "Straight-engine, automatic",
                             "Straight-engine, manual")
                  )+
scale_alpha_manual(name = "legend",
                   values = c(
                       "0" = 1,
                       "1"=2/5,
                       "0"=1,
                       "1"=2/5
                       ),
                   labels = c(
                       "V-engine, automatic", 
                       "V-engine, manual",
                       "Straight-engine, automatic",
                       "Straight-engine, manual"
                       )  )

Answer 1

我没有使用 aes(alpha) 来解决您的问题但治疗alpha如 fill.colour与 vs 的组合和 am .

mtcars %>% 
  ggplot(aes(gear, mpg, fill = interaction(as.factor(vs), as.factor(am)))) +
    geom_bar(stat = "identity") +
    scale_fill_manual(name = "legend",
                      values = c(
                          "0.0" = alpha("red", 1),
                          "1.0" = alpha("blue", 1),
                          "0.1" = alpha("red", 2/5),
                          "1.1" = alpha("blue", 2/5)
                          ),
                      labels = c("V-engine, automatic", 
                                 "V-engine, manual",
                                 "Straight-engine, automatic",
                                 "Straight-engine, manual")
                      )