Dataframe Column Switching

Question

I was wondering if there is a way to switch a column under an other one using a function. Basically if I have a dataframe as follow:

a <- data.frame("A" = 1:5, "B" = 2:6) 

  A B
1 1 2
2 2 3
3 3 4
4 4 5
5 5 6

I would like to get something like:

I don't see a reason for a down-vote, so I upvoted to counterbalance. — KoenV, Mar 22 '18 at 09:18

score 2 · Answer 1 · answered Mar 22 '18 at 09:03

2

One way you could achieve that is with stack :

a <- data.frame("A" = 1:5, "B" = 2:6) 
stack(a)

b <- stack(a)
dplyr::select(b, values)
   values
1       1
2       2
3       3
4       4
5       5
6       2
7       3
8       4
9       5
10      6

and you could of course write a shortcut function :

library(dplyr)
stack_cols <- function(df){
  stack(df) %>%
    select(values)
}

stack_cols(a)

   values
1       1
2       2
3       3
4       4
5       5
6       2
7       3
8       4
9       5
10      6

answered Mar 22 '18 at 09:03

Colin FAY

4,849
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1

Why use external package(s) when you can use base R : `stack(a)[,'values',drop=FALSE]` – digEmAll Mar 22 '18 at 09:07
Well, why not ? – Colin FAY Mar 22 '18 at 09:17
I assure you that in production environments, the less you need to install, the better it is ;) – digEmAll Mar 22 '18 at 09:26
1

I agree with that ! Indeed this is a better solution if the code is designed for production. – Colin FAY Mar 22 '18 at 09:28

score 2 · Answer 2 · answered Mar 22 '18 at 09:04

2

You could use unlist :

DF <- data.frame(A=unlist(a))
> DF
   A
A1 1
A2 2
A3 3
A4 4
A5 5
B1 2
B2 3
B3 4
B4 5
B5 6

answered Mar 22 '18 at 09:04

digEmAll

56,430
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140

score 2 · Answer 3 · answered Mar 22 '18 at 09:08

2

A very simple and straightforward way could be :

df <- data.frame(A=c(a$A, a$B))
> df
   A
1  1
2  2
3  3
4  4
5  5
6  2
7  3
8  4
9  5
10 6

answered Mar 22 '18 at 09:08

KoenV

4,113
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Dataframe Column Switching

3 Answers3