如何在组合 ggplot2 图中重新排序图？

Question

我已经看到了在仅绘制一个对象时重新排序子图的解决方案（例如mydata），但我不确定在绘制多个对象时如何执行此操作（在这种情况下，mydata1 和mydata2)。我想切换小提琴的顺序，使 Treatment2 在左侧，Treatment1 在右侧，而不是像我目前拥有的那样：

mycp <- ggplot() + geom_violin(data = mydata1, aes(x= treatment, y = Myc_List1, fill = Myc_List1, colour="Myc Pathway (Treatment1)")) + 
  geom_violin(data = mydata2, aes(x= treatment, y = Myc_List1, fill = Myc_List1, colour = "Myc Pathway (Treatment2)")) 

当我尝试Ordering of bars in ggplot 等解决方案或https://www.r-graph-gallery.com/22-order-boxplot-labels-by-names.html 提出的以下解决方案时，此图保持不变。

希望这是有道理的，感谢您的阅读！

更新

这是https://www.datanovia.com/en/blog/how-to-change-ggplot-legend-order/的另一个解决方案

mydata$treatment<- factor(mydata$treatment, levels = c("Treatment2", "Treatment1"))

Answer 1

我不确定在这种情况下如何重新排序因子，但您可以更改 x 轴比例以获得所需的结果，例如

library(tidyverse)

data("Puromycin")
dat1 <- Puromycin %>% 
  filter(state == "treated")
dat2 <- Puromycin %>% 
  filter(state == "untreated")

mycp <- ggplot() +
  geom_violin(data = dat1, aes(x= state, y = conc, colour = "Puromycin (Treatment1)")) + 
  geom_violin(data = dat2, aes(x= state, y = conc, colour = "Puromycin (Treatment2)")) 
mycp

mycp2 <- ggplot() +
  geom_violin(data = dat1, aes(x = state, y = conc, colour = "Puromycin (Treatment1)")) +
  geom_violin(data = dat2, aes(x = state, y = conc, colour = "Puromycin (Treatment2)")) +
  scale_x_discrete(limits = c("untreated", "treated"))
mycp2

Answer 2

将数据堆叠到单个数据帧中，并通过将treatment 转换为因子来设置顺序。在您的示例中，颜色和图例是多余的，因为您可以标记 x 轴值来描述每种治疗，或将 x 轴标题更改为“Myc Pathway”，但无论如何下面的代码都显示了如何获取订购。

library(tidyverse)

bind_rows(mydata1, mydata2) %>%
  mutate(treatment = factor(treatment, levels=paste0("Treatment", c(2,1)) %>%
  ggplot(aes(treatment, Myc_List1, colour=treatment)) +
    geom_violin()

这是一个可重现的例子：

library(tidyverse)
theme_set(theme_bw(base_size=15))

# Create two separate data frames to start with
d1=iris %>% filter(Species=="setosa")
d2=iris %>% filter(Species=="versicolor") 

bind_rows(d1, d2) %>% 
  mutate(Species = factor(Species, levels=c("versicolor", "setosa"))) %>% 
  ggplot(aes(Species, Petal.Width, colour=Species)) +
    geom_violin()