r - 如何清除所有属性？

Question

我想从数据中删除所有属性并应用 this solution .但是 one_entry() (原文)也不是我的one_entry2()会起作用，我不明白为什么。

one_entry2 <- function(x) {
  attr(x, "label") <- NULL
  attr(x, "labels") <- NULL
}

> lapply(df1, one_entry2)
$`id`
NULL

$V1
NULL

$V2
NULL

$V3
NULL

我们应该怎么做？

数据:

df1 <- setNames(data.frame(matrix(1:12, 3, 4)), 
                c("id", paste0("V", 1:3)))
attr(df1$V1, "labels") <- LETTERS[1:4]
attr(df1$V1, "label") <- letters[1:4]
attr(df1$V2, "labels") <- LETTERS[1:4]
attr(df1$V2, "label") <- letters[1:4]
attr(df1$V3, "labels") <- LETTERS[1:4]
attr(df1$V3, "label") <- letters[1:4]

> str(df1)
'data.frame':   3 obs. of  4 variables:
 $ id: int  1 2 3
 $ V1: int  4 5 6
  ..- attr(*, "labels")= chr  "A" "B" "C" "D"
  ..- attr(*, "label")= chr  "a" "b" "c" "d"
 $ V2: int  7 8 9
  ..- attr(*, "labels")= chr  "A" "B" "C" "D"
  ..- attr(*, "label")= chr  "a" "b" "c" "d"
 $ V3: int  10 11 12
  ..- attr(*, "labels")= chr  "A" "B" "C" "D"
  ..- attr(*, "label")= chr  "a" "b" "c" "d"

Answer 1

要删除所有属性，这个怎么样

df1[] <- lapply(df1, function(x) { attributes(x) <- NULL; x })
str(df1)
#'data.frame':  3 obs. of  4 variables:
# $ id: int  1 2 3
# $ V1: int  4 5 6
# $ V2: int  7 8 9
# $ V3: int  10 11 12