r - 将管道运算符 %>% 与 colnames()<- 等替换函数一起使用

Question

如何使用管道运算符通过管道连接到替换函数，如 colnames()<- ？

这就是我正在尝试做的事情:

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

但理想情况下它会是这样的:

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

有没有一种方法可以做到这一点，而无需每次都编写特殊函数？

这里的答案是一个开始，但不完全是我的问题:Chaining arithmetic operators in dplyr

Answer 1

您可以使用colnames<-或setNames (感谢@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

或者选择 Alias ( set_colnames ) 来自 magrittr :

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

dplyr::rename如果您仅(重新)命名许多列中的一些列，可能会更方便(它需要同时写入旧名称和新名称；请参阅@Richard Scriven 的答案)