r - 如何将一个简单的函数应用于多个列？

Question

我有以下数据框:

df <- data.frame("A" = c("y", "y", "n", "n"),
             "B" = c("n", NA, "y", "y"),
             "C" = c("n", "y", "y", "n"))

我想将以下代码应用于 A 列和 B 列:

df$A <- 
  df$A %>% 
  recode(
    "n" = "No",
    "y" = "Yes"
  ) %>% 
  factor(
    levels = c("No", "Yes")
  )

我尝试使用以下代码使用 for 循环来解决此问题:

cols <- c("A", "B")

for (i in cols) {
  df$i <- 
    df$i %>% 
    recode(
      "n" = "No",
      "y" = "Yes"
    ) %>% 
    factor(
      levels = c("No", "Yes")
    )
}

但是，我收到此错误消息:

Error in UseMethod("recode") : 
  no applicable method for 'recode' applied to an object of class "NULL"

任何人都可以帮我解决我在这里缺少的东西吗？感谢您的帮助!

Answer 1

使用 dplyr::across 你可以:

library(dplyr)

df <- data.frame("A" = c("y", "y", "n", "n"),
                 "B" = c("n", NA, "y", "y"),
                 "C" = c("n", "y", "y", "n"))

mutate(df, across(c(A, B), ~ recode(.x, "n" = "No","y" = "Yes") %>% factor(levels = c("No", "Yes"))))
#>     A    B C
#> 1 Yes   No n
#> 2 Yes <NA> y
#> 3  No  Yes y
#> 4  No  Yes n