On 18 May 2015 at 13:23, Dananji Liyanage wrote:

Hi All,

I'm building a 9x9 grid like list, and I want to extract each column of that grid.

My input is a list of integers as follows;

input = [0, 0, 0, 0, 0, 0, 4, 0, 9, 0, 0, 0, 0, 8, 0, 0, 5, 0, 7, 0, 2, 4, 5, 3, 6, 0, 0, 6, 7, 0, 0, 0, 1, 5, 0, 2, 2, 0, 8, 7, 0, 4, 3, 0, 1, 9, 0, 4, 5, 0, 0, 0, 8, 6, 0, 0, 6, 3, 1, 9, 8, 0, 7, 0, 2, 0, 0, 7, 0, 0, 0, 0, 1, 0, 7, 0, 0, 0, 0, 0, 0]

I tried list comprehension with 'take' function in lists as follows;

columns xs = [x | x <- (take 1 xs)] : columns (drop 9 xs) --> columns input

This extracts only the first column. How I can go for the other columns?

One easy way would be to first look at the `split` package to find the function `chunksOf` and then simply `Data.List.transpose` the result. /M -- Magnus Therning OpenPGP: 0xAB4DFBA4 email: magnus@therning.org jabber: magnus@therning.org twitter: magthe http://therning.org/magnus