如何使用ggplot2的layer()而非geom_histogram()绘制直方图并解决报错？

问题重现 #

你尝试用layer()替代geom_histogram()绘制直方图时遇到报错，代码及错误信息如下：

df <-data.frame(
sex <- rep(c("M","F"), each =50),
height <- round(c(rnorm(50, mean = 5.5, sd = .5), rnorm(50, mean = 4.8, sd = .8)),1)
)
df

library(ggplot2)
p <- ggplot()
p+ layer(data = df, geom = "histogram", mapping = aes(x=height, fill  = sex))
p+ layer(data = df, geom = "histogram", mapping = aes(x=height, fill  = sex), stat = "count")
p+ layer(data = df, geom = "histogram", mapping = aes(x=height, fill  = sex), stat = "count", position = "identity")

报错信息：

>>> p+ layer(data = df, geom = "histogram", mapping = aes(x=height, fill  = sex))
Error:
! Can't create layer without a stat.
Run `rlang::last_trace()` to see where the error occurred.


> p+ layer(data = df, geom = "histogram", mapping = aes(x=height, fill  = sex), stat = "count")
Error:
! Can't create layer without a position.
Run `rlang::last_trace()` to see where the error occurred.


> p+ layer(data = df, geom = "histogram", mapping = aes(x=height, fill  = sex), stat = "count", position = "identity")
Error:
! Can't find geom called "histogram"
Run `rlang::last_trace()` to see where the error occurred.

错误原因 #

1. 数据框创建错误：在data.frame()内部使用<-赋值会导致列名异常（实际列名会变成X.sex....和X.height....），后续aes(x=height)会找不到对应列。
2. geom参数错误：ggplot2中不存在名为"histogram"的geom，geom_histogram()是封装好的组合函数，底层实际调用的是geom="bar"配合stat="bin"——stat_bin负责将连续数据分箱计数，geom_bar负责绘制柱状图形。
3. stat参数错误：直方图需要用stat="bin"而非stat="count"，count是针对离散数据的计数统计，不符合直方图的连续数据分箱需求。

正确实现代码 #

步骤1：修正数据框创建

df <- data.frame(
  sex = rep(c("M","F"), each =50),
  height = round(c(rnorm(50, mean = 5.5, sd = .5), rnorm(50, mean = 4.8, sd = .8)),1)
)

步骤2：用layer()绘制直方图

library(ggplot2)
p <- ggplot()
# 基础版本：堆叠直方图
p + layer(
  data = df,
  geom = "bar",          # 直方图底层用bar geom
  stat = "bin",          # 用bin统计分箱
  mapping = aes(x=height, fill=sex),
  position = "stack"     # 堆叠显示不同性别，可选"identity"（重叠）或"dodge"（并列）
)

# 可选：指定分箱宽度与透明度
p + layer(
  data = df,
  geom = "bar",
  stat = "bin",
  mapping = aes(x=height, fill=sex),
  position = "identity",
  params = list(binwidth = 0.2, alpha = 0.7)
)

说明 #

geom_histogram()本质是layer(geom = "bar", stat = "bin", position = "stack", ...)的语法糖，直接用layer()时需要明确指定这几个核心参数。若需要并列直方图，可将position设为"dodge"；重叠显示则用"identity"并搭配alpha参数调整透明度。

内容的提问来源于stack exchange，提问作者user11254108