将平均值添加到ggplot中的直方图

Question

我在nycflights13软件包中为flights数据框的距离变量创建了一个直方图。

现在，我正在尝试向直方图添加一条垂直线以标记均值，如下所示：

library(nycflights13)
attach(flights)
ggplot(flights, aes(x = distance)) +
  geom_histogram(aes(y = ..density..), 
                 color = "darkblue", 
                 fill = "lightblue", 
                 binwidth = 250) +
  labs(x = "Departure delay (minutes)") +
  geom_vline(xintercept = mean(distance, color = black, size = 1.5)) +
  geom_density(color = "red", size = 1)

这给了我输出：

Warning messages:
1: In mean.default(distance, color = black, size = 1.5) :
  argument is not numeric or logical: returning NA
2: Removed 1 rows containing missing values (geom_vline).

我该如何解决？我尝试删除NA值，但我猜想方法不正确。

Answer 1

您需要放入mean作为标量。因此，我们可以在此处使用$。将颜色作为字符串"black"。

library(nycflights13)
# attach(flights)  # I strongly recommend not to use attach
library(ggplot2)
ggplot(flights, aes(x = distance)) +
  geom_histogram(aes(y = ..density..), 
                 color = "darkblue", 
                 fill = "lightblue", 
                 binwidth = 250) +
  labs(x = "Departure delay (minutes)") +
  geom_vline(xintercept = mean(flights$distance),
             color="black", size=1.5) +
  geom_density(color = "red", size = 1)