堆积折线图在ggplot中不起作用

library(ggplot2)

# 假设有三个分类变量，每个分类变量有三个时间点的数值
data <- data.frame(
  time = c(1, 2, 3),
  category1 = c(10, 20, 30),
  category2 = c(15, 25, 35),
  category3 = c(5, 15, 25)
)

# 数据预处理，计算累加值
data_cumsum <- data
data_cumsum[-1] <- apply(data[-1], 2, cumsum)

# 创建堆积折线图
ggplot(data_cumsum, aes(x = time)) +
  geom_line(aes(y = category1, color = "Category 1"), size = 1) +
  geom_line(aes(y = category2, color = "Category 2"), size = 1) +
  geom_line(aes(y = category3, color = "Category 3"), size = 1) +
  scale_color_manual(values = c("Category 1" = "red", "Category 2" = "blue", "Category 3" = "green")) +
  labs(x = "Time", y = "Value", title = "Stacked Line Chart") +
  theme_minimal()