[PD] list interlace ?

[Mathieu Bouchard]

On Thu, 8 Sep 2011, tim vets wrote:

> what's the best way to 'interlace' two lists, i.e. turn:
> 1 2 3 4 and 5 6 7 8
> into
> 1 5 2 6 3 7 4 8
> ?

It's usually called interleaving.

If they are all floats, the fastest is something like this :

[list prepend 1 4 f #]
  |
[#join 0]---------------[list prepend 1 4 f #]
  |
[#transpose]
  |
[#to_l]

where the 1 4 f # prefix means you want to make a grid of 1 row and 
4 columns of floats. Then in contact with grid-inlets, those prefixed 
lists become grids of 1 by 4.

[#join] joins them by the dimension 0, which makes a single grid of 
(1+1=2) rows by 4 columns.

[transpose] swaps the first two dimensions, which makes a grid of 4 
rows by 2 columns.

[#to_l] makes a list of 8 elements, row after row.

Of course you can instead use a [list append] and messagebox containing :

   $1 $5 $2 $6 $3 $7 $4 $8

and in that particular case, it's more efficient, but the GridFlow 
solution works for any list length, and is probably more efficient for big 
lists...

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| Mathieu Bouchard ---- tél: +1.514.383.3801 ---- Villeray, Montréal, QC