当数据类别不同时如何在多个堆叠条形图上获得相同的图例类别ggplot2

library(tidyverse)

# 创建示例数据
data <- data.frame(
  x = c("A", "B", "C"),
  y1 = c(10, 20, 30),
  y2 = c(15, 25, 35),
  y3 = c(5, 15, 25)
)

# 转换为长格式
data_long <- data %>% gather(category, value, -x)

library(ggplot2)

# 绘制堆叠条形图
ggplot(data_long, aes(x = x, y = value, fill = category)) +
  geom_bar(stat = "identity") +
  scale_fill_manual(values = c("A" = "red", "B" = "blue", "C" = "green"))