删除geom_histogram的基线颜色 [英] Remove baseline color for geom_histogram

问题描述

我要在多面直方图中添加 color 美观度.在下面的reprex中，没有颜色美感，直方图仅显示该构面级别内的数据.但是，在定义了 color 的情况下，添加了一个基线，该基线将拉伸范围扩展到包括所有方面的数据范围.有没有办法使这种情况不发生?

我正在寻找与 triom = TRUE 的 geom_density 类似的东西，但是 geom_histogram .

 库(tidyverse)数据<-tibble(a = rchisq(1000，df = 3)，b = rchisq(1000，df = 1)，c ＝ rchisq(1000，df ＝ 10))％＞％收集()ggplot(数据，aes(x =值))+geom_histogram()+facet_wrap(〜键，ncol = 1)#>使用bins = 30的stat_bin().用`binwidth`选择更好的价值. 

  ggplot(data，aes(x = value))+geom_histogram(color ="red")+facet_wrap(〜键，ncol = 1)#>使用bins = 30的stat_bin().用`binwidth`选择更好的价值. 

  ggplot(data，aes(x = value))+geom_density(color ="red"，trim = TRUE)+facet_wrap(〜键，ncol = 1) 

^由

在这种情况下，如果我们检查与直方图图层关联的数据帧，则有许多行，其中 ymin = ymax = 0问题中看到的基准效果.

  p<-ggplot(数据，aes(x =值))+geom_histogram(color ="red")+facet_wrap(〜键，ncol = 1)View(layer_data(p)％>％filter(PANEL == 2))#查看与构面面板2相关的数据 

解决方法:由于数据计算是在 StatBin 的 compute_group 函数中完成的，因此我们可以定义该函数的替代版本，并通过附加步骤删除该函数.完全对数据框中的行进行零计数:

StatBin2的

 #修改版继承自StatBin，但#compute_group()函数中的最后第二行StatBin2<-ggproto("StatBin2"，StatBin，compute_group =函数(数据，小数位数，binwidth = NULL，bins = NULL，中心= NULL，边界= NULL，已关闭= c("right"，"left")，pad = FALSE，breaks = NULL，origin = NULL，right = NULL，降= NULL，宽度= NULL){如果(！is.null(breaks)){如果(！scales $ x $ is_discrete()){中断<-缩放$ x $ transform(breaks)}箱<-ggplot2 ::: bin_breaks(休息，已关闭)}否则if(！is.null(binwidth)){如果(is.function(binwidth)){binwidth<-binwidth(data $ x)}bins<-ggplot2 ::: bin_breaks_width(scales $ x $ dimension()，binwidth，中心=中心，边界=边界，已关闭=已关闭)}别的 {bins<-ggplot2 ::: bin_breaks_bins(scales $ x $ dimension()，bins，中心=中心，边界=边界，已关闭=已关闭)}res<-ggplot2 ::: bin_vector(data $ x，bins，weight = data $ weight，pad = pad)#在返回数据帧之前完全删除0计数箱res<-res [res $ count>0，]资源}) 

用法:

  ggplot(data，aes(x = value))+geom_histogram(color ="red"，stat = StatBin2)+#指定stat = StatBin2facet_wrap(〜键，ncol = 1) 

I'm adding a color aesthetic to a faceted histogram. In the reprex below, with no color aesthetic, the histogram only show data within that facet level. However, with color defined, a baseline is added which stretches the stretches to include the range of data across all facets. Is there a way to make this not happen?

I'm looking for something similar to geom_density with trim = TRUE, but there doesn't appear to be a trim option for geom_histogram.

library(tidyverse)

data <- tibble(a = rchisq(1000, df = 3),
               b = rchisq(1000, df = 1),
               c = rchisq(1000, df = 10)) %>%
  gather()

ggplot(data, aes(x = value)) +
  geom_histogram() +
  facet_wrap(~ key, ncol = 1)
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

ggplot(data, aes(x = value)) +
  geom_histogram(color = "red") +
  facet_wrap(~ key, ncol = 1)
#> `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

ggplot(data, aes(x = value)) +
  geom_density(color = "red", trim = TRUE) +
  facet_wrap(~ key, ncol = 1)

^{Created on 2019-07-20 by the reprex package (v0.3.0)}

解决方案

geom_histogram draws its bars using using rectGrob from the grid package, and a zero-width / zero-height rectGrob is depicted as a vertical / horizontal line in the outline colour, at least in my set-up for RStudio (& OP's as well, I presume). Demonstration below:

library(grid)

r1 <- rectGrob(width = unit(0, "npc"), gp = gpar(col = "red", fill = "grey")) # zero-width
r2 <- rectGrob(height = unit(0, "npc"), gp = gpar(col = "red", fill = "grey")) # zero-height

grid.draw(r1) # depicted as a vertical line, rather than disappear completely
grid.draw(r2) # depicted as a horizontal line, rather than disappear completely

In this case, if we check the data frame associated with the histogram layer, there are many rows with ymin = ymax = 0, which are responsible for the 'baseline' effect seen in the question.

p <- ggplot(data, aes(x = value)) +
  geom_histogram(color = "red") +
  facet_wrap(~ key, ncol = 1)

View(layer_data(p) %>% filter(PANEL == 2)) # look at the data associated with facet panel 2

Workaround: Since the data calculations are done in StatBin's compute_group function, we can define an alternative version of the same function, with an additional step to drop the 0-count rows from the data frame completely:

# modified version of StatBin2 inherits from StatBin, except for an
# additional 2nd last line in compute_group() function
StatBin2 <- ggproto(
  "StatBin2", 
  StatBin,
  compute_group = function (data, scales, binwidth = NULL, bins = NULL, 
                            center = NULL, boundary = NULL, 
                            closed = c("right", "left"), pad = FALSE, 
                            breaks = NULL, origin = NULL, right = NULL, 
                            drop = NULL, width = NULL) {
    if (!is.null(breaks)) {
      if (!scales$x$is_discrete()) {
        breaks <- scales$x$transform(breaks)
      }
      bins <- ggplot2:::bin_breaks(breaks, closed)
    }
    else if (!is.null(binwidth)) {
      if (is.function(binwidth)) {
        binwidth <- binwidth(data$x)
      }
      bins <- ggplot2:::bin_breaks_width(scales$x$dimension(), binwidth, 
                                         center = center, boundary = boundary, 
                                         closed = closed)
    }
    else {
      bins <- ggplot2:::bin_breaks_bins(scales$x$dimension(), bins, 
                                        center = center, boundary = boundary, 
                                        closed = closed)
    }
    res <- ggplot2:::bin_vector(data$x, bins, weight = data$weight, pad = pad)

    # drop 0-count bins completely before returning the dataframe
    res <- res[res$count > 0, ] 

    res
  })

Usage:

ggplot(data, aes(x = value)) +
  geom_histogram(color = "red", stat = StatBin2) + # specify stat = StatBin2
  facet_wrap(~ key, ncol = 1)

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