merge (opposite of split) pair of rows in r
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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).

    mydataf <- data.frame (Ind = 1:5, col1a = sample (c(1:3), 5, replace = T), 
       col1b = sample (c(1:3), 5, replace = T),  colNa = sample (c(1:3), 5, replace = T),
       colNb = sample (c(1:3),5, replace = T),
         K_a = sample (c("A", "B"),5, replace = T),  
        K_b = sample (c("A", "B"),5, replace = T))

    mydataf 
       Ind col1a col1b colNa colNb K_a K_b
    1   1     1     1     2     3   B   A
    2   2     1     3     2     2   B   B
    3   3     2     1     1     1   B   B
    4   4     3     1     1     3   A   B
    5   5     1     1     3     2   B   A

Except First column (Ind), I want to collapse the pair of rows to make the dataframe look like the following, at the sametime the suffix "a" and "b" be removed. Also merged characters or number be ordered 1 first that 2, A first than B

       Ind col1   colN  K_
        1   11     23   AB   
        2   13     22   BB
        3   12     11   BB
        4   13     13   AB
        5   11     23   AB   
