在facet_wrap图中添加"浮动"轴标签

Question

我和这个用户有同样的问题- 我有一个'锯齿状'刻面图,其中底行的面板比其他行少,我想在每列的底部有x轴刻度.

该问题的建议解决方案是设置scales="free_x".(在ggplot 0.9.2.1中;我相信我正在寻找的行为在早期版本中是默认的.)在我的情况下,这是一个糟糕的解决方案:我的实际轴标签会相当长,所以将它们放在每一行下会占用太多房间.结果是这样的:

 x <- gl(3, 1, 15, labels=paste("this is a very long axis label ", letters[1:5]))
 y <- rnorm(length(x))
 l <- gl(5, 3, 15)
 d <- data.frame(x=x, y=y, l=l)
 ggplot(d, aes(x=x, y=y)) + geom_point() + facet_wrap(~l, scales="free_x") + 
   theme(axis.text.x=element_text(angle=90, hjust=1))

在这里的评论中,Andrie建议可以手动完成,grid但我不知道如何开始.

Answer 1

如果我没记错的话,对于如何将所有标签添加到最后一列下的同一行以及如何将这些最后标签提升到下一行存在疑问.所以这是两种情况的功能:

编辑:因为这就像print.ggplot(见getAnywhere(print.ggplot))的替代品我已经添加了一些行来保留功能.

编辑2:我有更多的改进吧:不需要指定nrow和ncol了,所有的面板图可以印得.

library(grid)
# pos - where to add new labels
# newpage, vp - see ?print.ggplot
facetAdjust <- function(x, pos = c("up", "down"), 
                        newpage = is.null(vp), vp = NULL)
{
  # part of print.ggplot
  ggplot2:::set_last_plot(x)
  if(newpage)
    grid.newpage()
  pos <- match.arg(pos)
  p <- ggplot_build(x)
  gtable <- ggplot_gtable(p)
  # finding dimensions
  dims <- apply(p$panel$layout[2:3], 2, max)
  nrow <- dims[1]
  ncol <- dims[2]
  # number of panels in the plot
  panels <- sum(grepl("panel", names(gtable$grobs)))
  space <- ncol * nrow
  # missing panels
  n <- space - panels
  # checking whether modifications are needed
  if(panels != space){
    # indices of panels to fix
    idx <- (space - ncol - n + 1):(space - ncol)
    # copying x-axis of the last existing panel to the chosen panels 
    # in the row above
    gtable$grobs[paste0("axis_b",idx)] <- list(gtable$grobs[[paste0("axis_b",panels)]])
    if(pos == "down"){
      # if pos == down then shifting labels down to the same level as 
      # the x-axis of last panel
      rows <- grep(paste0("axis_b\\-[", idx[1], "-", idx[n], "]"), 
                   gtable$layout$name)
      lastAxis <- grep(paste0("axis_b\\-", panels), gtable$layout$name)
      gtable$layout[rows, c("t","b")] <- gtable$layout[lastAxis, c("t")]
    }
  }
  # again part of print.ggplot, plotting adjusted version
  if(is.null(vp)){
    grid.draw(gtable)
  }
  else{
    if (is.character(vp)) 
      seekViewport(vp)
    else pushViewport(vp)
    grid.draw(gtable)
    upViewport()
  }
  invisible(p)
}

这是它的外观

d <- ggplot(diamonds, aes(carat, price, fill = ..density..)) +
  xlim(0, 2) + stat_binhex(na.rm = TRUE) + theme(aspect.ratio = 1) + 
  facet_wrap(~ color)
facetAdjust(d)

facetAdjust(d, "down")

编辑3:

这是一种替代解决方案,上面的解决方案也很好.

当一个人想和他们ggsave一起使用时会有一些问题facetAdjust.类的的曲线ggplot是必需的因为两个部分中的源代码ggsave:print(plot)和default_name(plot)在情况下,一个没有手动(根据提供的文件名?ggsave似乎它是不应该工作,虽然).因此,给定一个文件名,有一个解决方法(在某些情况下可能有副作用):

首先,让我们考虑实现浮动轴主效应的单独函数.通常,它会返回一个gtable对象,但是我们使用它class(gtable) <- c("facetAdjust", "gtable", "ggplot").通过这种方式,它可以根据需要使用ggsave和print(plot)工作(见下文print.facetAdjust)

facetAdjust <- function(x, pos = c("up", "down"))
{
  pos <- match.arg(pos)
  p <- ggplot_build(x)
  gtable <- ggplot_gtable(p); dev.off()
  dims <- apply(p$panel$layout[2:3], 2, max)
  nrow <- dims[1]
  ncol <- dims[2]
  panels <- sum(grepl("panel", names(gtable$grobs)))
  space <- ncol * nrow
  n <- space - panels
  if(panels != space){
    idx <- (space - ncol - n + 1):(space - ncol)
    gtable$grobs[paste0("axis_b",idx)] <- list(gtable$grobs[[paste0("axis_b",panels)]])
    if(pos == "down"){
      rows <- grep(paste0("axis_b\\-[", idx[1], "-", idx[n], "]"), 
                   gtable$layout$name)
      lastAxis <- grep(paste0("axis_b\\-", panels), gtable$layout$name)
      gtable$layout[rows, c("t","b")] <- gtable$layout[lastAxis, c("t")]
    }
  }
  class(gtable) <- c("facetAdjust", "gtable", "ggplot"); gtable
}

打印功能仅相差几行ggplot2:::print.ggplot:

print.facetAdjust <- function(x, newpage = is.null(vp), vp = NULL) {
  if(newpage)
    grid.newpage()
  if(is.null(vp)){
    grid.draw(x)
  } else {
    if (is.character(vp)) 
      seekViewport(vp)
    else pushViewport(vp)
    grid.draw(x)
    upViewport()
  }
  invisible(x)
}

例:

d <- ggplot(diamonds, aes(carat, price, fill = ..density..)) +
  xlim(0, 2) + stat_binhex(na.rm = TRUE) + theme(aspect.ratio = 1) + 
  facet_wrap(~ color)
p <- facetAdjust(d) # No output
print(p) # The same output as with the old version of facetAdjust()
ggsave("name.pdf", p) # Works, a filename is necessary