Binding columns with similar column names in the same dataframe in R

Question

I have a data frame that looks somewhat like this:

df <- data.frame(0:2, 1:3, 2:4, 5:7, 6:8, 2:4, 0:2, 1:3, 2:4)
colnames(df) <- rep(c(\'a\', \'b\', \         


        

Answer 1

Use %in% and some unlisting

zz <- lapply(unique(names(df)), function(x,y) as.vector(unlist(df[which(y %in% x)])),y=names(df))
names(zz) <- unique(names(df))
as.data.frame(zz)
  a b c
1 0 1 2
2 1 2 3
3 2 3 4
4 5 6 2
5 6 7 3
6 7 8 4
7 0 1 2
8 1 2 3
9 2 3 4