r - 如何在R中使用facet_wrap绘制并排箱线图？

Question

我正在寻找一种在R中使用facet_wrap并排绘制boxplot的解决方案。尽管有很多好的解决方案，但是我没有遇到我想要的。我决定画一张我希望看到的两个 data.frame 的 plot 的图片。 Data.frame C 有我针对不同度量的四种模型(即 KGE、NSE、PBIAS 和 R-Sq)的校准数据而 Data.frame V 有我的验证数据。我想使用ggplot2 功能的facet_wrap 查看每个指标的单独plot。以下是我到目前为止所做的事情，但它并没有让我更接近。

graphics.off()
rm(list = ls())

library(tidyverse)

C = data.frame(KGE_M1 = runif(3, 0, 0.5), NSE_M1 = runif(3,0,0.5), R_Sq_M1 = runif(3,-1,0.3), PBIAS_M1 = runif(3, -0.25, 0.25),
               KGE_M2 = runif(3, 0.2, 0.7), NSE_M2 = runif(3,0.2,0.7), R_Sq_M2 = runif(3,-0.5,0.7), PBIAS_M2 = runif(3, -0.15, 0.15),
               KGE_M3 = runif(3, 0.3, 0.8), NSE_M3 = runif(3,0.3,0.8), R_Sq_M3 = runif(3,0.3,0.8), PBIAS_M3 = runif(3, -0.10, 0.10),
               KGE_M4 = runif(3, 0.5, 1), NSE_M4 = runif(3,0.5,1), R_Sq_M4 = runif(3,0.5,1), PBIAS_M4 = runif(3, -0.05, 0.05),
               Cal = rep("Calibration", 3))

V = data.frame(KGE_M1 = runif(3, 0, 0.5), NSE_M1 = runif(3,0,0.5), R_Sq_M1 = runif(3,-1,0.3), PBIAS_M1 = runif(3, -0.25, 0.25),
               KGE_M2 = runif(3, 0.2, 0.7), NSE_M2 = runif(3,0.2,0.7), R_Sq_M2 = runif(3,-0.5,0.7), PBIAS_M2 = runif(3, -0.15, 0.15),
               KGE_M3 = runif(3, 0.3, 0.8), NSE_M3 = runif(3,0.3,0.8), R_Sq_M3 = runif(3,0.3,0.8), PBIAS_M3 = runif(3, -0.10, 0.10),
               KGE_M4 = runif(3, 0.5, 1), NSE_M4 = runif(3,0.5,1), R_Sq_M4 = runif(3,0.5,1), PBIAS_M4 = runif(3, -0.05, 0.05),
               Val = rep("Validation", 3))

C = gather(C, key = "Variable", value = "Value", -Cal)
V = gather(V, key = "Variable", value = "Value", -Val)

ggplot(data = C)+
  geom_boxplot(aes(x= Variable, y = Value))
  + facet_wrap(~Variable)

我想看到如下所示的情节

Answer 1

我认为您需要在绘图之前拆分您的变量，以便为 M1、M2、M3 M4 提供一个变量，并为您的条件提供一个变量:

library(tidyverse)
C2 <- C %>% pivot_longer(., -Cal, names_to = "Variable", values_to = "Value") %>%
  group_by(Variable) %>%
  mutate(Variable2 = unlist(strsplit(Variable, "_M"))[2]) %>%
  mutate(Variable2 = paste0("Cal_M",Variable2)) %>%
  mutate(Variable1 = unlist(strsplit(Variable,"_M"))[1])  %>%
  rename(., Type = Cal)

# A tibble: 6 x 5
# Groups:   Variable [6]
  Type        Variable  Value Variable2 Variable1
  <fct>       <chr>     <dbl> <chr>     <chr>    
1 Calibration KGE_M1    0.246 Cal_M1    KGE      
2 Calibration NSE_M1    0.476 Cal_M1    NSE      
3 Calibration R_Sq_M1  -0.978 Cal_M1    R_Sq     
4 Calibration PBIAS_M1  0.117 Cal_M1    PBIAS    
5 Calibration KGE_M2    0.544 Cal_M2    KGE      
6 Calibration NSE_M2    0.270 Cal_M2    NSE   

现在，我们对数据集 V 做同样的事情

V2 <- V %>% pivot_longer(., -Val, names_to = "Variable", values_to = "Value") %>%
  group_by(Variable) %>%
  mutate(Variable2 = unlist(strsplit(Variable, "_M"))[2]) %>%
  mutate(Variable2 = paste0("Val_M",Variable2)) %>%
  mutate(Variable1 = unlist(strsplit(Variable,"_M"))[1]) %>%
  rename(., Type = Val)

# A tibble: 6 x 5
# Groups:   Variable [6]
  Type       Variable   Value Variable2 Variable1
  <fct>      <chr>      <dbl> <chr>     <chr>    
1 Validation KGE_M1    0.459  Val_M1    KGE      
2 Validation NSE_M1    0.105  Val_M1    NSE      
3 Validation R_Sq_M1  -0.435  Val_M1    R_Sq     
4 Validation PBIAS_M1  0.0281 Val_M1    PBIAS    
5 Validation KGE_M2    0.625  Val_M2    KGE      
6 Validation NSE_M2    0.332  Val_M2    NSE    

我们现在可以将它们绑定(bind)在一起:

DF <- rbind(C2,V2)

然后，我们可以绘制:

ggplot(DF, aes(x = Variable2, y = Value))+
  geom_boxplot()+
  facet_wrap(.~Variable1, scales = "free")+
  theme(axis.text.x = element_text(angle = 45, hjust = 1))

编辑:重命名 x 轴，添加空列以单独的校准和验证值

要在校准和验证之间添加空白，您只需为 Variable1 的每个条件添加空行，如下所示:

DF <- as.data.frame(DF) %>% add_row(Type = rep("Empty",4),
                     Variable = rep("Empty",4),
                     Value = rep(NA,4),
                     Variable2 = rep("Empty",4),
                     Variable1 = unique(DF$Variable1))

此外，如果您想重命名x轴标签，可以使用scale_x_discrete

ggplot(DF, aes(x = Variable2, y = Value, fill = Type))+
  geom_boxplot()+
  facet_wrap(.~Variable1, scales = "free")+
  theme(axis.text.x = element_text(angle = 45, hjust = 1))+
  scale_x_discrete(labels = c("M1","M2","M3","M4","","M1","M2","M3","M4"))

它看起来符合你的期望吗？