这是一个利用 ggplot 的 sec.axis 参数的 hack,它创建了一个与主轴相反的辅助轴,并且必须是它的一对一映射。我称之为 hack,因为这仅适用于连续轴,因此我们需要将分类 Propvalue 映射到数值。
注意:在本例中,我假设您希望所有奇数 PropX 刻面标签在左侧,偶数 PropX 刻面标签在右侧。您还可以调整其他变体的选项。
library(ggplot2)
library(tidyverse)
# generate data
set.seed(10)
df<-data.frame(Meas = runif(1000,0,10),
Prop1 = sample(x = LETTERS[1:3],1000,replace=TRUE),
Prop2 = sample(x=c("monkey","donkey","flipper"),1000,replace=TRUE),
Prop3 = sample(x = letters[1:5],1000,replace=TRUE))%>%
gather(Prop,Propvalue,-Meas)
# map Propvalue to integers, primary axis contents, & secondary axis contents.
df2 <- df %>%
mutate(Propvalue.int = as.integer(factor(Propvalue,
levels = df %>% select(Prop, Propvalue) %>%
arrange(Prop, Propvalue) %>% unique() %>%
select(Propvalue) %>% unlist())),
facet.column = ifelse(as.integer(str_extract(Prop, "[0-9]")) %% 2 == 0, 2, 1),
Propvalue.left = ifelse(facet.column == 1, Propvalue, ""),
Propvalue.right = ifelse(facet.column == 2, Propvalue, ""))
# create mapping table
integer2factor <- df2 %>%
select(Propvalue.int, Propvalue.left, Propvalue.right) %>%
unique() %>% arrange(Propvalue.int)
ggplot(df2,aes(x = Propvalue.int, y=Meas,
group = Propvalue.int))+
geom_boxplot() +
scale_x_continuous(breaks = integer2factor$Propvalue.int,
labels = integer2factor$Propvalue.left,
name = "Propvalue",
sec.axis = dup_axis(breaks = integer2factor$Propvalue.int,
labels = integer2factor$Propvalue.right,
name = "")) +
facet_wrap(~Prop,ncol=2,scales="free")+
coord_flip() +
theme(axis.ticks.y = element_blank())