问ggplot2 (R)：Error msg：‘错误:美学必须长度为1或与数据相同(1093)：x，y’

EN

library(tidyr)
library(ggplot2)
library(scales)

df <- data.frame(g = 0.936871,
                 t = 0.063129)

df <- gather(df, variable, value)

ggplot(df, aes(x = variable, y = value)) +
  geom_bar(stat = "identity") +
  scale_y_continuous(labels = percent)

df <- data.frame(
  category = c(1, 2),
  g = c(0.8070175, 0.97099768),
  t = c(0.1929825, 0.029000232)
)

df <- gather(df, variable, value, -category)

ggplot(df, aes(x = category, y = value)) +
  geom_col(aes(fill = variable), position = position_dodge()) +
  scale_y_continuous(labels = percent) +
  scale_x_discrete(limits = c(1,2), breaks = c(1,2), labels = c("Category 1", "Category 2"))