merge (opposite of split) pair of rows in r

Question

I have the column like the following. Each column has two pairs each with suffix \"a\" and \"b\" - for example col1a, col1b, colNa, colNb and so on till end of the file (> 50000

Answer 1

mydataf
  Ind col1a col1b colNa colNb K_a K_b
1   1     2     1     1     1   A   A
2   2     1     2     1     3   B   A
3   3     1     2     3     2   A   A
4   4     1     2     3     1   A   B
5   5     1     2     2     1   A   A
n <- names(mydataf)
nm <- c("Ind", unique(substr(n, 1, nchar(n)-1)[-1]))
df <- data.frame(sapply(nm, function(x){
                             idx <- grep(paste0(x, "[ab]?$"), n)
                             cols <- mydataf[idx]
                             x <- apply(cols, 1, 
                                       function(z) paste(sort(z), collapse = ""))
                             return(x)
                            }))
names(df) <- nm
df
  Ind col1 colN K_
1   1   12   11 AA
2   2   12   13 AB
3   3   12   23 AA
4   4   12   13 AB
5   5   12   12 AA