我试着把一条线性回归线画成一张散点图,在x轴上有一个有序的分类变量.但是,我的代码没有绘制线条(也没有警告或错误).可以画出绝对x轴的回归线吗?也许我必须具体说明group
级的顺序?明确设置级别并没有帮助.
# libraries
library(ggplot2)
# dummy data
dat <- data.frame(group = as.factor(c(rep("A", 10), rep("B", 10))),
variable = c(rnorm(10, mean = 3), rnorm(10, mean = 12)))
# specify order of levels explicitly
dat$group <- factor(dat$group, levels = c("A", "B"))
# plot
ggplot(dat, aes(x = group, y = variable)) +
geom_point() +
geom_smooth(method = "lm")
输出: