如何使用ggplot2动态地封装facet标签 [英] How to dynamically wrap facet label using ggplot2
问题描述
我正在寻找一种动态地将条形标签文本包装在 facet_wrap
或 facet_grid
调用中的方法。我找到了一种使用 strwrap
完成此操作的方法,但我需要指定宽度
以使输出生效如预期的。通常情况下,facelet的数量并不是预先知道的,所以这种方法需要我根据数据集和绘图大小迭代调整 width
参数。是否有可能为wrap函数动态指定宽度,还是有另外一个选项可以更好地标记facet?
I'm looking for a way to dynamically wrap the strip label text in a facet_wrap
or facet_grid
call. I've found a way to accomplish this using strwrap
, but I need to specify a width
for the output to work as desired. Often the number of facets is not known in advance, so this method requires me to iteratively adjust the width
parameter based on the dataset and plot size. Is it possible to dynamically specify a width for the wrap function, or is there another option for labeling facets that would work better?
library(ggplot2)
df = expand.grid(group=paste(c("Very Very Very Long Group Name "), 1:9),
x=rnorm(5), y=rnorm(5), stringsAsFactors=FALSE)
df$groupwrap = unlist(lapply(strwrap(df$group, width=30, simplify=FALSE), paste,
collapse="\n"))
p = ggplot(df) +
geom_point(aes(x=x, y=y)) +
facet_wrap(~groupwrap)
更新:根据@baptiste和@thunk提供的指导,我提出了下面的选项。目前,它只适用于指定的字体系列和大小,但理想情况下,应该也可以使用默认的主题
设置。也许有更多 ggplot2
经验的人有一些改进建议。
UPDATE: Based on the guidance provided by @baptiste and @thunk, I came up with the option below. Currently, it only works for a specified font family and size, but ideally, one should be able to also use the default theme
settings. Maybe someone with more ggplot2
experience has some suggestions for improvement.
library('grid')
grobs <- ggplotGrob(p)
sum = sum(sapply(grobs$width, function(x) convertWidth(x, "in")))
panels_width = par("din")[1] - sum # inches
df$group = as.factor(df$group)
npanels = nlevels(df$group)
if (class(p$facet)[1] == "wrap") {
cols = n2mfrow(npanels)[1]
} else {
cols = npanels
}
ps = 12
family = "sans"
pad = 0.01 # inches
panel_width = panels_width / cols
char_width = strwidth(levels(df$group)[
which.max(nchar(levels(df$group)))], units="inches", cex=ps / par("ps"),
family=family) / max(nchar(levels(df$group)))
width = floor((panel_width - pad)/ char_width) # characters
df$groupwrap = unlist(lapply(strwrap(df$group, width=width, simplify=FALSE),
paste, collapse="\n"))
ggplot(df) +
geom_point(aes(x=x, y=y)) +
facet_wrap(~groupwrap) +
theme(strip.text.x=element_text(size=ps, family=family))
推荐答案
感谢@baptiste和@thunk的指导,我创建了下面的函数,它似乎在自动换行符标签方面做得非常好。不过,欢迎您提出改进建议。
Thanks to the guidance from @baptiste and @thunk, I created the function below, which seems to do a pretty good job of automatically wrapping facet labels. Suggestions for improvement are always welcome, though.
strwrap_strip_text = function(p, pad=0.05) {
# get facet font attributes
th = theme_get()
if (length(p$theme) > 0L)
th = th + p$theme
require("grid")
grobs <- ggplotGrob(p)
# wrap strip x text
if ((class(p$facet)[1] == "grid" && !is.null(names(p$facet$cols))) ||
class(p$facet)[1] == "wrap")
{
ps = calc_element("strip.text.x", th)[["size"]]
family = calc_element("strip.text.x", th)[["family"]]
face = calc_element("strip.text.x", th)[["face"]]
if (class(p$facet)[1] == "wrap") {
nm = names(p$facet$facets)
} else {
nm = names(p$facet$cols)
}
# get number of facet columns
levs = levels(factor(p$data[[nm]]))
npanels = length(levs)
if (class(p$facet)[1] == "wrap") {
cols = n2mfrow(npanels)[1]
} else {
cols = npanels
}
# get plot width
sum = sum(sapply(grobs$width, function(x) convertWidth(x, "in")))
panels_width = par("din")[1] - sum # inches
# determine strwrap width
panel_width = panels_width / cols
mx_ind = which.max(nchar(levs))
char_width = strwidth(levs[mx_ind], units="inches", cex=ps / par("ps"),
family=family, font=gpar(fontface=face)$font) /
nchar(levs[mx_ind])
width = floor((panel_width - pad)/ char_width) # characters
# wrap facet text
p$data[[nm]] = unlist(lapply(strwrap(p$data[[nm]], width=width,
simplify=FALSE), paste, collapse="\n"))
}
if (class(p$facet)[1] == "grid" && !is.null(names(p$facet$rows))) {
ps = calc_element("strip.text.y", th)[["size"]]
family = calc_element("strip.text.y", th)[["family"]]
face = calc_element("strip.text.y", th)[["face"]]
nm = names(p$facet$rows)
# get number of facet columns
levs = levels(factor(p$data[[nm]]))
rows = length(levs)
# get plot height
sum = sum(sapply(grobs$height, function(x) convertWidth(x, "in")))
panels_height = par("din")[2] - sum # inches
# determine strwrap width
panels_height = panels_height / rows
mx_ind = which.max(nchar(levs))
char_height = strwidth(levs[mx_ind], units="inches", cex=ps / par("ps"),
family=family, font=gpar(fontface=face)$font) /
nchar(levs[mx_ind])
width = floor((panels_height - pad)/ char_height) # characters
# wrap facet text
p$data[[nm]] = unlist(lapply(strwrap(p$data[[nm]], width=width,
simplify=FALSE), paste, collapse="\n"))
}
invisible(p)
}
要使用该函数,请将其替换为 print
。
To use the function, call it in place of print
.
library(ggplot2)
df = expand.grid(group=paste(c("Very Very Very Long Group Name "), 1:4),
group1=paste(c("Very Very Very Long Group Name "), 5:8),
x=rnorm(5), y=rnorm(5), stringsAsFactors=FALSE)
p = ggplot(df) +
geom_point(aes(x=x, y=y)) +
facet_grid(group1~group)
strwrap_strip_text(p)
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