如何在x轴上使用ggplot2和facet_work而不丢弃组内的因子

您可以通过使用ggh4x程序包来获得您想要的结果，该程序包允许您 for each 面单独设置刻度，例如，您可以这样做:

library(ggplot2)
library(ggh4x)

ggplot(
  df.all,
  aes(
    x = cr,
    y = val
  )
) +
  geom_violin() +
  geom_point(
    position = position_jitter(width = 0.1, height = 0.1),
    alpha = .3
  ) +
  facet_wrap(vars(ps, id),
    scales = "free_x",
    ncol = 4
  ) +
  facetted_pos_scales(
    x = list(
      ps == "gc1" ~ scale_x_discrete(limits = c("A", "B", "C")),
      ps == "ps1" ~ scale_x_discrete(limits = c("D", "E", "F"))
    )
  )

EDIT这里是根据在ps个组上循环的数据动态创建比例的一种方法，并使用reformulate为facetted_pos_scales创建formula:

library(ggplot2)
library(ggh4x)

scale_x <- lapply(unique(df.all$ps), \(x) {
  reformulate(
    paste0("scale_x_discrete(limits=sort(unique(df.all$cr[df.all$ps =='", x, "'])))"),
    paste0("ps == '", x, "'")
  )  
})

ggplot(
  df.all,
  aes(
    x = cr,
    y = val
  )
) +
  geom_violin() +
  geom_point(
    position = position_jitter(width = 0.1, height = 0.1),
    alpha = .3
  ) +
  facet_wrap(vars(ps, id),
    scales = "free_x",
    ncol = 4
  ) +
  facetted_pos_scales(
    x = scale_x
  )