在每个方面而不是整体上显示摘要行 [英] Display a summary line per facet rather than overall

问题描述

我正在尝试类似于此问题，但希望在单个块中完成此操作，而不是分别缓存值.

I am trying to do something similar to this question, but hoping to do it in a single block rather than caching values separately.

我正在创建与此类似的图表:

I am creating a chart similar to this:

library(tidyverse)

mtcars %>%
  rownames_to_column("carmodel") %>%
  mutate(brand = substr(carmodel, 1, 4)) %>%
  group_by(brand, cyl) %>%
  summarize(avgmpg = mean(mpg)) %>%
  ggplot(aes(x=brand, y = avgmpg)) +
  geom_point() +
  facet_grid(cyl~., scales = "free_y") +
  coord_flip()

按一个字段分组，然后在结果上绘制计算出的summarize()值，并使用构面将相似的观察值放在一起.我想做的是在每个构面中添加一条线，以显示该构面的观测值的平均值.我尝试将geom_hline(aes(yintercept = mean(avgmpg)))添加到定义中，但是它返回整个数据集的平均值，而不是构面中的观察值:

Grouping by one of the fields, and then charting a calculated summarize() value on the result, using facets to place similar observations together. What I would like to do is add a line in each facet showing the mean of the observations for that facet. I have tried adding geom_hline(aes(yintercept = mean(avgmpg))) to the definition, but it returns the mean for the entire dataset, not the observations in the facet:

我追求的是这样的. (这里的线是用图像编辑器绘制的.)

What I'm after is more like this. (The lines here are drawn with an image editor.)

这可能吗?

推荐答案

由于您说过要在一个块中完成，请注意，在.的许多用法中，您可以在几何图形中使用它来引用原始的ggplot()的数据参数.因此，您可以在此处进行其他汇总以获取geom_vline的值.我也只是颠倒了geom_point中的美观，而不是使用coord_flip.

Because you said you wanted to do it in one block, note that among the many uses of . you can use it in geoms to refer to the original data argument to ggplot(). So here you can do an additional summarise to get the values for geom_vline. I also just reversed the aesthetics in geom_point instead of using coord_flip.

library(tidyverse)

mtcars %>%
  rownames_to_column("carmodel") %>%
  mutate(brand = substr(carmodel, 1, 4)) %>%
  group_by(brand, cyl) %>%
  summarize(avgmpg = mean(mpg)) %>%
  ggplot(aes(y=brand, x = avgmpg)) +
  geom_point() +
  geom_vline(
    data = . %>%
      group_by(cyl) %>%
      summarise(line = mean(avgmpg)),
    mapping = aes(xintercept = line)
    ) +
  facet_grid(cyl~., scales = "free_y")

reprex软件包(v0.2.0)于2018-06-21创建.

Created on 2018-06-21 by the reprex package (v0.2.0).

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