将％>％与colnames（）<- [英] use %>% with replacement functions like colnames()<-

问题描述

如何使用管道运算符将管道函数插入诸如 colnames（）<-的替换函数中？

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

这是我要执行的操作：

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

但是理想的情况是像这样：

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"))

是否有一种无需每次都编写特殊函数的方法？

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

这是一个开始，但不完全是我的问题tion：在dplyr中束缚算术运算符

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 （感谢到@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

或从 magrittr <中选择别名（ set_colnames ） / code>：

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 可能更方便如果您只是（重）命名多列中的几列（它需要同时写旧名称和新名称；参见@Richard Scriven的答案）

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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