r - 如何在R中匹配不同组合的字符串

Question

我有一个数据框 df，单词由 + 分隔，但我不希望在执行分析时顺序很重要。例如，我有

df <- as.data.frame(
      c(("Yellow + Blue + Green"),
        ("Blue + Yellow + Green"),
        ("Green + Yellow + Blue")))

目前，它们被视为三个独特的响应，但我希望它们被视为相同。我尝试过蛮力方法，例如 ifelse 语句，但它们不适合大型数据集。

有没有一种方法可以重新排列这些术语，使它们匹配，或者像反向 combn 函数那样识别它们是相同的组合但顺序不同？

谢谢!

Answer 1

#DATA
df <- data.frame(cols = 
                 c(("Yellow + Blue + Green"),
                   ("Blue + Yellow + Green"),
                   ("Green + Yellow + Blue"),
                   ("Green + Yellow + Red")), stringsAsFactors = FALSE)

#Split, sort, and then paste together
df$group = sapply(df$cols, function(a)
    paste(sort(unlist(strsplit(a, " \\+ "))), collapse = ", "))
df
#                   cols               group
#1 Yellow + Blue + Green Blue, Green, Yellow
#2 Blue + Yellow + Green Blue, Green, Yellow
#3 Green + Yellow + Blue Blue, Green, Yellow
#4  Green + Yellow + Red  Green, Red, Yellow

#Or you can convert to factors too (and back to numeric, if you like)
df$group2 = as.numeric(as.factor(sapply(df$cols, function(a)
        paste(sort(unlist(strsplit(a, " \\+ "))), collapse = ", "))))
df
#                   cols               group group2
#1 Yellow + Blue + Green Blue, Green, Yellow      1
#2 Blue + Yellow + Green Blue, Green, Yellow      1
#3 Green + Yellow + Blue Blue, Green, Yellow      1
#4  Green + Yellow + Red  Green, Red, Yellow      2