From: Sebastian Hungerecker <sepp2k@...>
Date: 2009-03-08T02:13:07+09:00
Subject: Re: how to un-ragged a 2D array?

Phlip wrote:
> Here's a ragged array:
>
>   [ [ 1    ],
>     [ 2, 3 ],
>     [ 4    ],
>     [ 5, 6 ],
>     [ 7    ],
>     [ 8    ] ]
>
> How, with the tightest, or most modern, or coolest statements, can we turn
> it into this?
>
>   [ [ 1, 1 ],
>     [ 2, 3 ],
>     [ 4, 4 ],
>     [ 5, 6 ],
>     [ 7, 7 ],
>     [ 8, 8 ] ]

I'm making the following assumptions:
a) we have variable "size" which contains the size of a full subarray
b) subarrays should be filled by repeating the last element until the subarray
   is full.

array = [ [ 1    ],
        [ 2, 3 ],
        [ 4    ],
        [ 5, 6 ],
        [ 7    ],
        [ 8    ] ]
size  = 2
array.map do |subarray|
  subarray + [subarray.last] * (size - subarray.size)
end
# => [ [1, 1],
       [2, 3],
       [4, 4],
       [5, 6],
       [7, 7],
       [8, 8] ]

HTH,
Sebastian