r - 粘贴多列(奇怪的行为)

Question

我试图将多个具有相同名称的列粘贴到一个新行中，但我遇到了一些奇怪的行为。示例:

x <- data.frame(x = 1:10, y= 2:11, z= 11:20)
colnames(x) <- c("x", "y", "x")
x
> x
    x  y  x
1   1  2 11
2   2  3 12
3   3  4 13
4   4  5 14
5   5  6 15
6   6  7 16
7   7  8 17
8   8  9 18
9   9 10 19
10 10 11 20
# now I try to paste columns to rows 

> x2 <- data.frame(columns = unique(colnames(x)), 
+                  values = sapply(1:length(unique(colnames(x))), function(i)
+                    paste(x[,(which(unique(colnames(x))[i]==colnames(x)))], collapse = ", ")))
> x2
  columns                         values
1       x                    1:10, 11:20
2       y 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

我想要的只是

> x2
columns                         values
1       x 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
2       y 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

有人可以帮我防止这种行为吗？

Answer 1

x <- data.frame(x = 1:10, y= 2:11, z= 11:20)
colnames(x) <- c("x", "y", "x")
unique_cols <- unique(colnames(x))
x2 <- sapply(unique_cols, function(s) unlist(x[, unique_cols == s], use.names = F))
x2

$x
[1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20
$y
[1]  2  3  4  5  6  7  8  9 10 11

和

typeof(x2)
[1] "list"

如果您需要具有折叠值的数据框:

df <- data.frame(columns = unique_cols,
                 value = as.character(sapply(x2, function(s) paste(s, collapse = ","), USE.NAMES = F)))

df

  columns                                              value
1       x 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20
2       y                              2,3,4,5,6,7,8,9,10,11