如何在R dataframe中使用来自多个列的有序项生成新列

我在R中有一个数据帧，如下所示：

df <-
data.frame(
"first_col" = c("apple", "apple", "banana", "banana", "cacao", "dough"),
"second_col" = c("apple", "apple", "banana", "banana", "apple", "dough"),
"third_col" = c("banana", "apple", "banana", "banana", "banana", "apple"),
stringsAsFactors = FALSE
)

df$label <- paste(sort(df$first_col,
                                     df$second_col,
                                     df$third_col),
                              sep = " - ")

  first_col second_col third_col
1     apple      apple    banana
2     apple      apple     apple
3    banana     banana    banana
4    banana     banana    banana
5     cacao      apple    banana
6     dough      dough     apple

  first_col second_col third_col                       label
1     apple      apple    banana      apple - apple - banana
2     apple      apple     apple       apple - apple - apple
3    banana     banana    banana    banana - banana - banana
4    banana     banana    banana    banana - banana - banana
5     cacao      apple    banana      apple - banana - cacao
6     dough      dough     apple       apple - dough - dough

很明显我做错了什么。查看文档，该方法似乎需要一个向量，因此我尝试通过这样做将其向量化

df$label <- paste(sort(c(df$first_col,
                                   df$second_col,
                                   df$third_col)),
                              sep = " - ")

我想得到这样的东西：

df <-
data.frame(
"first_col" = c("apple", "apple", "banana", "banana", "cacao", "dough"),
"second_col" = c("apple", "apple", "banana", "banana", "apple", "dough"),
"third_col" = c("banana", "apple", "banana", "banana", "banana", "apple"),
stringsAsFactors = FALSE
)

df$label <- paste(sort(df$first_col,
                                     df$second_col,
                                     df$third_col),
                              sep = " - ")

  first_col second_col third_col
1     apple      apple    banana
2     apple      apple     apple
3    banana     banana    banana
4    banana     banana    banana
5     cacao      apple    banana
6     dough      dough     apple

  first_col second_col third_col                       label
1     apple      apple    banana      apple - apple - banana
2     apple      apple     apple       apple - apple - apple
3    banana     banana    banana    banana - banana - banana
4    banana     banana    banana    banana - banana - banana
5     cacao      apple    banana      apple - banana - cacao
6     dough      dough     apple       apple - dough - dough

---

您可以通过查看第5行和第6行来判断是否已排序。

使用

base

：

df$combined<-apply(df,1,function(x) paste(sort(x),collapse="-"))
 df
  first_col second_col third_col               combined
1     apple      apple    banana   apple-apple-banana
2     apple      apple     apple    apple-apple-apple
3    banana     banana    banana banana-banana-banana
4    banana     banana    banana banana-banana-banana
5     cacao      apple    banana   apple-banana-cacao
6     dough      dough     apple    apple-dough-dough

---

df$组合使用
dplyr
mutate（）
和
purrr
pmap（）

库（dplyr）
图书馆（purrr）
df%
mutate（label=pmap（列表（第一列，第二列，第三列），函数（x，y，z）粘贴（排序（c（x，y，z）），collapse=“-”）
#第一列第二列第三列标签
#1苹果香蕉苹果-苹果-香蕉
#2苹果-苹果-苹果
#3香蕉-香蕉-香蕉
#4香蕉-香蕉-香蕉
#5可可苹果香蕉苹果-香蕉-可可
#6面团苹果-面团-面团
您可以添加您的预期输出吗？@NelsonGon我更新了问题，希望现在更好。谢谢，这就可以了。如果我只想在我拥有的三个列中选择两个列来生成新列，该怎么办？您的解决方案使用所有列。我可以先选择所有列，然后在这里应用该方法，但在我看来这不是最好的方法。如果我只想使用列1和列2，可以使用如下选择：
df[c（1,2）]
。注意，答案名为df
df
as
df3
，因为我有一些其他的
df
用于其他答案。
df <- structure(list(first_col = c("apple", "apple", "banana", "banana", 
"cacao", "dough"), second_col = c("apple", "apple", "banana", 
"banana", "apple", "dough"), third_col = c("banana", "apple", 
"banana", "banana", "banana", "apple"), sorted = c("apple-apple-banana", 
"apple-apple-apple", "banana-banana-banana", "banana-banana-banana", 
"apple-banana-cacao", "apple-dough-dough")), row.names = c(NA, 
-6L), class = "data.frame")

library(dplyr)
library(purrr)

df <-
  data.frame(
    "first_col" = c("apple", "apple", "banana", "banana", "cacao", "dough"),
    "second_col" = c("apple", "apple", "banana", "banana", "apple", "dough"),
    "third_col" = c("banana", "apple", "banana", "banana", "banana", "apple"),
    stringsAsFactors = FALSE
  )

df %>% 
  mutate(label = pmap(list(first_col, second_col, third_col), function(x, y, z) paste(sort(c(x,y,z)), collapse = " - ")))

# first_col second_col third_col                    label
# 1     apple      apple    banana   apple - apple - banana
# 2     apple      apple     apple    apple - apple - apple
# 3    banana     banana    banana banana - banana - banana
# 4    banana     banana    banana banana - banana - banana
# 5     cacao      apple    banana   apple - banana - cacao
# 6     dough      dough     apple    apple - dough - dough