ggplot中geom_col+coord_polar方向异常（色块标签顺序不符）修复咨询

问题代码 #

library(ggplot2)
library(dplyr)

set.seed(2501)
sample_data <- data.frame(name=LETTERS[1:7], val=runif(7,0,1))

ggplot(sample_data) +
  geom_col(aes(x=1, y=val, fill=name), just = 0, width = 1) +
  geom_text(aes(x=1.5, y=val, label=name),
            position = position_stack(vjust = 0.5)) +
  xlim(c(0, 2)) +
  coord_polar(theta = "y", start = 0, direction = 1) +
  theme_void() +
  theme(axis.text = element_blank(),
        legend.title = element_blank(),
        axis.ticks = element_blank(),
        axis.line = element_blank())

问题现象 #

环形图效果展示：彩色分段为逆时针顺序，标签为顺时针顺序，二者方向不一致

设置coord_polar(theta = "y", direction = 1)后，预期环形分段按顺时针排列，但实际彩色分段方向与标签方向相反。

修复方法 #

问题根源是geom_col默认的堆叠方向与position_stack在极坐标下的表现不匹配。只需给geom_col添加position = position_stack(reverse = TRUE)参数，反转柱子的堆叠方向，就能让分段顺序和标签一致。

修改后的完整代码：

library(ggplot2)
library(dplyr)

set.seed(2501)
sample_data <- data.frame(name=LETTERS[1:7], val=runif(7,0,1))

ggplot(sample_data) +
  geom_col(aes(x=1, y=val, fill=name), 
           position = position_stack(reverse = TRUE),
           just = 0, width = 1) +
  geom_text(aes(x=1.5, y=val, label=name),
            position = position_stack(vjust = 0.5)) +
  xlim(c(0, 2)) +
  coord_polar(theta = "y", start = 0, direction = 1) +
  theme_void() +
  theme(axis.text = element_blank(),
        legend.title = element_blank(),
        axis.ticks = element_blank(),
        axis.line = element_blank())

原理说明 #

position_stack(reverse = TRUE)会反转geom_col的堆叠顺序，使其与coord_polar(direction=1)的顺时针方向对齐，同时保持geom_text的标签位置逻辑不变，最终实现分段和标签的顺序一致。

内容的提问来源于stack exchange，提问作者Miles N.