在自定义函数中使用dplyr mutate_at

我想从一个表中取两个变量，然后将它们除以第三个变量，然后将这些计算作为两个新列添加。

mutate_at（）

非常接近我，但是在下面的自定义函数

f（）

中，我想访问数据集中的另一列。有什么建议或替代方法吗

library(dplyr)
# this works fine but is NOT what I want
f <- function(fld){
  fld/5
}

# This IS what I want where wt is a field in the data
f <- function(fld){
  fld/wt
}

mutate_at(mtcars, .vars = vars(mpg, cyl), .funs = funs(xyz = f))

# This works but is pretty clumsy
f <- function(fld, dat) fld/dat$wt
mutate_at(mtcars, .vars = vars(mpg, cyl), .funs = funs(xyz = f(., mtcars)))

# This is closer but still it would be better if the function allowed the dataset to be submitted to the function without restating the name of the dataset

f <- function(fld, second){
  fld/second
}

mutate_at(mtcars, .vars = vars(mpg, cyl), .funs = funs(xyz = f(., wt)))

库（dplyr）
#这很好，但不是我想要的
也许是这样的

f <- function(fld,var){
    fld/var
}

mtcars %>%
    mutate_at(vars(mpg,cyl), .funs = funs(xyz = f(.,wt)))

为什么不简单

mutate(mtcars, mpg2 = mpg / wt, cyl2 = cyl / wt)

这适用于几个字段，但不灵活，如果有10个字段，会很麻烦。如果你改变了对后缀（“2”）的想法，你必须在几个地方改变它。同意，我想我错过了你问题的关键
mutate(mtcars, mpg2 = mpg / wt, cyl2 = cyl / wt)

library(tidyverse)
f <- function(num, denom) num/denom

mtcars %>% 
  mutate_at(vars(mpg, cyl), f, denom = quote(wt))

mtcars %>% 
  mutate_at(vars(mpg, cyl), `/`, quote(wt))