下面是一个简单的代码,用于使用Facet_WRAP绘制条形图:
categories <- c("category 1", "category 2", "category 3")
groups <- c("A", "B", "C", "D")
df <- expand.grid(category = categories, group = groups)
df$value <- rnorm(12, 1, 0.5)
ggplot(df, aes(x = category,
y = value)) +
geom_bar(stat = "identity") +
facet_wrap(~ group)
现在,我希望C组的条形为红色(仅用于C组).我该怎么做呢?