Question

如何将多列数据帧转换为两列数据帧。

例如，我有一个包含四列的数据集

    foo<-data.frame(

            w= rnorm(10, mean=50, sd=10),
            x= sample(1:10, 10, replace=T),
            y=c("red", "red", "red", "blue", "blue", 
                "blue", "yellow", "yellow", "yellow", 
                "green"),
            z=runif(10, 5.0, 7.5))

      w         x      y        z
      42.67991  8    red 7.460069
      46.40567  5    red 6.159747
      65.67709  8    red 7.352203
      57.53091  4   blue 5.838025
      37.31885  1   blue 5.486540
      46.38344  5   blue 5.848174
      50.65255  1 yellow 7.434667
      45.31212  1 yellow 7.449169
      49.10322 10 yellow 6.611908
      39.10083 10  green 6.539835

我试图将这四列数据帧转换为两列数据帧（a，b），如下所示

      a             b
      42.67991      8    
      46.40567      5    
      .             .
      .             .
      red           7.460069
      red           6.159747
      .             .
      .             .
      8             red 
      5             red
      .             .
      .             .
      42.67991      red 
      46.40567      red 
      .     .
      .             .

      42.67991      7.460069
      46.40567      6.159747
      .             .
      .             .
      8             7.460069
      5             6.159747

非常感谢任何帮助。

Answer 1

尝试

indx <- combn(1:ncol(foo), 2)
res <-  do.call(rbind,lapply(split(indx, col(indx)), function(i) {
                 x1 <- foo[i]
                 colnames(x1) <- letters[1:2]
                x1}))

row.names(res) <- NULL
head(res)
#        a b
#1 42.67991 8
#2 46.40567 5
#3 65.67709 8
#4 57.53091 4
#5 37.31885 1
#6 46.38344 5

或者

res1 <-  do.call(rbind,combn(1:ncol(foo), 2, FUN= function(i) 
                       list(setNames(foo[i], letters[1:2]))))

数据

foo <- structure(list(w = c(42.67991, 46.40567, 65.67709, 57.53091, 
37.31885, 46.38344, 50.65255, 45.31212, 49.10322, 39.10083), 
x = c(8L, 5L, 8L, 4L, 1L, 5L, 1L, 1L, 10L, 10L), y = c("red", 
"red", "red", "blue", "blue", "blue", "yellow", "yellow", 
"yellow", "green"), z = c(7.460069, 6.159747, 7.352203, 5.838025, 
5.48654, 5.848174, 7.434667, 7.449169, 6.611908, 6.539835
)), .Names = c("w", "x", "y", "z"), class = "data.frame",
 row.names = c(NA, -10L))

将多列数据帧转换为两列数据帧

1 个答案:

数据