R: Collapse multiple boolean columns into single attribute column with new rows for each combination [duplicate]

Question

This question already has an answer here:

• Converting multiple boolean columns to single factor column 4 answers

Trying to melt or collapse a dataframe with multiple boolean columns into a two column database with an id column and a column for the collapsed values BUT each value results in a new row.

Example beginning:

      A S1 S2 S3 S4
1   ex1  1  0  0  0
2   ex2  0  1  0  0
3   ex3  0  0  1  0
4   ex4  1  1  0  0
5   ex5  0  1  0  1
6   ex6  0  1  0  0
7   ex7  1  1  1  0
8   ex8  0  1  1  0
9   ex9  0  0  1  0
10 ex10  1  0  0  0

Desired output:

A   Type
ex1 S1
ex2 S2
ex3 S3
ex4 S1
ex4 S2
ex5 S2
ex5 S4
ex6 S2
ex7 S1
ex7 S2
ex7 S3
ex8 S2
ex8 S3
ex9 S3
ex10 S1

Thanks in advance!

Answer 1

in base R:

 subset(cbind(A=dat[,1],stack(dat[-1])),values==1,-2)
      A ind
1   ex1  S1
4   ex4  S1
7   ex7  S1
10 ex10  S1
12  ex2  S2
14  ex4  S2
15  ex5  S2
16  ex6  S2
17  ex7  S2
18  ex8  S2
23  ex3  S3
27  ex7  S3
28  ex8  S3
29  ex9  S3
35  ex5  S4

In the tidyverse:

library(tidyverse)
dat%>%
   gather(Type,j,-A)%>%
   filter(j==1)%>%
   select(-j)
      A Type
1   ex1   S1
2   ex4   S1
3   ex7   S1
4  ex10   S1
5   ex2   S2
6   ex4   S2
7   ex5   S2
8   ex6   S2
9   ex7   S2
10  ex8   S2
11  ex3   S3
12  ex7   S3
13  ex8   S3
14  ex9   S3
15  ex5   S4