geom_tile和facet_grid/facet_wrap用于相同高度的图块

Question

使用ggplot,我想用面板表示图形图块,但每个面板使用相同的高度图块.我有这个图:

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))

但是瓷砖的高度在面板之间是不同的.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))

解决了瓷砖高度的问题,但面板(组1 ...组3)的标签不在面板的顶部.是否可以使用facet_grid更改面板标签的位置？或者组合facet_grid和facet_wrap？谢谢你的帮助,对不起我的英语!

Answer 1

您可以在绘图之前查看ggplot包含的内容,并相应地重新调整面板.

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)