From: Chauk-Mean Proum <chauk.mean@...>
Date: 2009-06-17T00:34:36+09:00
Subject: Extracting and inserting a "column" from/into an array

Hi,

For image processing, I have to do the following operations :

1/ I have an array and I want to extract every 4 element into another
array :

# r=red, g=green, b=blue, a=alpha
img_data = [ "r1", "g1", "b1", "a1", "r2, "g2", "b2", "a2" ]

=> [ "a1", "a2" ]  # the array of every four elements i.e. alpha data

It's like extracting the fourth column of a matrix of n rows and 4
columns.

2/ Conversely, I have an array and I need to add elements at every 3
elements

img_data = [ "r1", "g1", "b1", "r2, "g2", "b2" ]
alpha_data = [ "a1", "a2" ] # the elements to add

=> [ "r1", "g1", "b1", "a1", "r2, "g2", "b2", "a2" ]

It's like inserting a column to a matrix of n rows and 3 columns.

I'm wondering if there is an easy or seamless way to do these
operations.
Thanks in advance for any tips.

Cheers.

Chauk-Mean.
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