geom_tile 和 facet_grid/facet_wrap 用于相同高度的瓷砖

Question

使用 ggplot，我想用面板表示一个图形图块，但每个面板的图块高度相同。 我有这张图：

dataSta <- list(sites=rep(paste("S", 1:31),each=12), month=rep(1:12,31), value=round(runif(31*12, min=0, max=3000)), panel=c(rep("Group 1",16*12),rep("Group 2", 12*12), rep("Group 3", 3*12)))

    library(ggplot2)
    library(grid)
    base_size <- 9

    windows()
    ggplot(data.frame(dataSta), aes(factor(month), sites)) + 
      geom_tile(aes(fill = value), colour = "black")+
      facet_wrap(~panel, scale="free_y", nrow=3)+
      theme_grey(base_size = base_size) +  
      labs(x = "",y = "") + 
      scale_x_discrete(expand = c(0, 0)) +    
      scale_y_discrete(expand = c(0, 0)) +    
      theme(legend.title = element_blank(),
            axis.ticks = element_blank(),     
            axis.text.x = element_text(size = base_size *0.8, hjust = 0),
            panel.margin = unit(0,"lines"),
            strip.text = element_text(colour="red3", size=10, face=2))

但面板之间的瓷砖高度不同。我尝试使用 facet_grid ：

windows()
ggplot(data.frame(dataSta), aes(factor(month), sites)) + 
  geom_tile(aes(fill = value), colour = "black")+
  facet_grid(panel~., scales="free_y", space="free")+
  theme_grey(base_size = base_size) +  
  labs(x = "",y = "") + 
  scale_x_discrete(expand = c(0, 0)) +    
  scale_y_discrete(expand = c(0, 0)) +    
  theme(legend.title = element_blank(),
        axis.ticks = element_blank(),     
        axis.text.x = element_text(size = base_size *0.8, hjust = 0),
        panel.margin = unit(0,"lines"),
        strip.text = element_text(colour="red3", size=10, face=2))

瓷砖高度的问题已解决，但面板（第 1 组 ... 第 3 组）的标签不在面板顶部。是否可以使用 facet_grid 更改面板标签的位置？或结合 facet_grid 和 facet_wrap ？ 感谢您的帮助，对不起我的英语！

Answer 1

ggforce 包有一个简洁的小功能，称为facet_col。它不需要搞乱grid 包！

您所要做的就是用适当的 facet_col 替代调用替换对 facet_grid 的调用：

library(ggplot2)
library(ggforce)

dataSta <- list(sites=rep(paste("S", 1:31),each=12), 
month=rep(1:12,31), value=round(runif(31*12, min=0, max=3000)), 
panel=c(rep("Group 1",16*12),rep("Group 2", 12*12), rep("Group 3", 3*12)))

base_size <- 9

ggplot(data.frame(dataSta), aes(factor(month), sites)) + 
  geom_tile(aes(fill = value), colour = "black") +

  # Here's the line to alter:
  facet_col(vars(panel), , scales = "free_y", space = "free") +

  theme_grey(base_size = base_size) +  
  labs(x = "",y = "") + 
  scale_x_discrete(expand = c(0, 0)) +    
  scale_y_discrete(expand = c(0, 0)) +    
  theme(legend.title = element_blank(),
        axis.ticks = element_blank(),     
        axis.text.x = element_text(size = base_size *0.8, hjust = 0),
        panel.spacing = unit(0,"lines"),
        strip.text = element_text(colour="red3", size=10, face=2))

Answer 2

我花了一些时间找到更简单的解决方案，它实际上是facet_grid 的一部分，您可以在其中设置space = "free_y"。更多信息请访问recent question。

Answer 3

您可以在绘图前查看 ggplot 包含的内容，并相应地重新缩放面板。

g <- ggplot_build(p) 
## find out how many y-breaks are in each panel
## to infer the number of tiles
vtiles <- sapply(lapply(g$panel$ranges, "[[", "y.major"), length)

## convert the plot to a gtable object 
gt <- ggplot_gtable(g)
## find out which items in the layout correspond to the panels
## we refer to the "t" (top) index of the layout
panels <- gt$layout$t[grepl("panel", gt$layout$name)]
## replace the default panel heights (1null) with relative sizes 
## null units scale relative to each other, so we scale with the number of tiles
gt$heights[panels] <-lapply(vtiles, unit, "null")
## draw on a clean slate
library(grid)
grid.newpage()
grid.draw(gt)