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ggplot2 0.9.2中的数学符号

ggplot2 r

4

Tyler Rinker DaniM · 技术社区 · 13 年前

当您想将数学符号添加到 facet_wrap 你过去可以使用 grid 包装如 (example taken from here) 以下为:

library(ggplot2); library(grid)
d <- ggplot(diamonds, aes(carat, price, fill = ..density..)) 
    xlim(0, 2) + stat_binhex(na.rm = TRUE) + opts(aspect.ratio = 1)
d <- d + facet_wrap(~ color, ncol = 4)
grob <- ggplotGrob(d)
strip_elem <- grid.ls(getGrob(grob, "strip.text.x", grep=TRUE, global=TRUE))$name
grob <- editGrob(grob, strip_elem[1], label=expression(Y[1]))
grid.draw(grob)

这不再有效,因为它会出现以下错误:

>  strip_elem <- grid.ls(getGrob(grob, "strip.text.x", grep=TRUE, global=TRUE))$name
Error in getGrob(grob, "strip.text.x", grep = TRUE, global = TRUE) : 
  It is only valid to get a child from a 'gTree'
> grob <- editGrob(grob, strip_elem[1], label=expression(Y[1]))
Error in editGrob(grob, strip_elem[1], label = expression(Y[1])) : 
  object 'strip_elem' not found

我们如何在0.9.2版本中添加数学符号?

1 回复 | 直到 9 年前

1

4

Community Mohan Dere 9 年前

使现代化 使用facet_wrap_labeller函数可能更容易 available from here 。

library(ggplot2)
library(gtable)

d <- ggplot(diamonds, aes(carat, price, fill = ..density..)) +
    xlim(0, 2) + stat_binhex(na.rm = TRUE) + theme(aspect.ratio = 1)
(d <- d + facet_wrap(~color, ncol = 4))    

facet_wrap_labeller <- function(gg.plot, labels=NULL) {
  require(gridExtra)

  g <- ggplotGrob(gg.plot)
  gg <- g$grobs      
  strips <- grep("strip_t", names(gg))

  for(ii in seq_along(labels))  {
    modgrob <- getGrob(gg[[strips[ii]]], "strip.text", 
                       grep=TRUE, global=TRUE)
    gg[[strips[ii]]]$children[[modgrob$name]] <- editGrob(modgrob,label=labels[ii])
  }

  g$grobs <- gg
  class(g) = c("arrange", "ggplot",class(g)) 
  return(g)
}

# Some arbitrary strip texts
StripTexts = expression(Y[1], E, F, G, H, I, J)

# Apply the facet_wrap_labeller function
g = facet_wrap_labeller(d, StripTexts)

# Draw it
g

原始解决方案 通过一个小的编辑,使选择条形文本变得更容易。

这很管用,但在中间有点乱。它使用 ggplot2 0.9.2 和来自 grid 和 gtable 包装。必须有一种更简单的方法,我希望你能从中吸取一些东西,找到一个更简单的解决方案。

步骤如下:

绘制原始绘图;
找到需要更换的条形元件;
提取条形元素;
将“D”更改为 expression(Y[1]) ;

将修改后的条形元素重新插入到原始绘图中。

library(ggplot2); library(grid); library(gtable)
d <- ggplot(diamonds, aes(carat, price, fill = ..density..)) +
    xlim(0, 2) + stat_binhex(na.rm = TRUE) + theme(aspect.ratio = 1)
(d <- d + facet_wrap(~color, ncol = 4))    
# The aim is to change the strip text "D" to expression(Y[1])

# Winston's accessor function:
gt_getgrob <- function(gt, pattern) {
  idx <- grep(pattern, gt$layout$name)
  if (length(idx) > 1)
    stop("More than one match for pattern '", pattern, "'")
  gt$grobs[[idx]]
}

g = ggplotGrob(d)
g$layout    # We want "strip_t-1"
strip <- gt_getgrob(g, "t-1")        # Use the accessor function to extract it.
str(strip)     # Locate the "D" label

strip$children[[2]]$label = expression(Y[1])    # Change the label.
grid.draw(strip)       # Yes, it's worked

gt <- ggplot_gtable(ggplot_build(d))  
gtable_show_layout(gt)       # Get the layout of the original plot.

gt = gtable_add_grob(gt, strip, t=3, l=4, b=3, r=4)  # Insert the modified strip element into the plot.
grid.newpage()
grid.draw(gt)

结果是:

enter image description here