将 %>% 与 colnames()<- 等替换函数一起使用

问题描述

我如何使用管道操作符将替换函数输入到替换函数中，例如 colnames() ?

How can I use the pipe operator to pipe into replacement function like colnames()<- ?

这是我想要做的:

library(dplyr)
averages_df <-
   group_by(mtcars, cyl) %>%
   summarise(mean(disp), mean(hp))
colnames(averages_df) <- c("cyl", "disp_mean", "hp_mean")
averages_df

# Source: local data frame [3 x 3]
#
#   cyl disp_mean   hp_mean
# 1   4  105.1364  82.63636
# 2   6  183.3143 122.28571
# 3   8  353.1000 209.21429

但理想情况下应该是这样的:

But ideally it would be something like:

averages_df <-
  group_by(mtcars, cyl) %>%
  summarise(mean(disp), mean(hp)) %>%
  add_colnames(c("cyl", "disp_mean", "hp_mean"))

有没有办法不用每次都写一个专门的函数?

Is there a way to do this without writing a specialty function each time?

这里的答案是一个开始，但不完全是我的问题:在 dplyr 中链接算术运算符

The answers here are a start, but not exactly my question: Chaining arithmetic operators in dplyr

推荐答案

您可以使用 colnames<- 或 setNames(感谢@David Arenburg)

You could use colnames<- or setNames (thanks to @David Arenburg)

group_by(mtcars, cyl) %>%
  summarise(mean(disp), mean(hp)) %>%
  `colnames<-`(c("cyl", "disp_mean", "hp_mean"))
  # or
  # `names<-`(c("cyl", "disp_mean", "hp_mean"))
  # setNames(., c("cyl", "disp_mean", "hp_mean"))

#   cyl disp_mean   hp_mean
# 1   4  105.1364  82.63636
# 2   6  183.3143 122.28571
# 3   8  353.1000 209.21429

或者从 magrittr 中选择一个 Alias (set_colnames):

Or pick an Alias (set_colnames) from magrittr:

library(magrittr)
group_by(mtcars, cyl) %>%
  summarise(mean(disp), mean(hp)) %>%
  set_colnames(c("cyl", "disp_mean", "hp_mean"))

dplyr::rename 如果您只是(重新)命名许多列中的一些列可能会更方便(它需要同时编写旧名称和新名称；请参阅@Richard Scriven 的回答)

dplyr::rename may be more convenient if you are only (re)naming a few out of many columns (it requires writing both the old and the new name; see @Richard Scriven's answer)

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