Nested loops and array formation

Question

Suppose that I start with an array that looks like:

$array_1 = array(array(1,2,3), array(2,4,5), array(3,6,7));

For simplicity, assume that I have a rule that says: delete the first subarray and then delete the first elements of the remaining subarrays. This would yield the result:

$new_array  = array(array(4,5), array(6,7))

Then assume I expand the problem to larger arrays like:

$array_2 = array(array(1,2,3,4), array(2,3,4,5), array(3,4,5,6), array(4,5,6,7));

I have the same rule here - delete first subarray and then delete first elements of the remaining subarrays. BUT this rule must be continued until the smallest subarray contains only two elements (as in the first example). So that in stage one of the process, my new array would look like:

$new_array_s1 = array(array(3,4,5), array(4,5,6), array(5,6,7));

But in the final stage, the completed array would look like:

$new_array_s2 = array(array(5,6), array(6,7));

For context, here is my code for the $array_1 example:

<?php

$array_1 = array(array(1,2,3), array(2,4,5), array(3,6,7));
$array_shell = $array_1;
unset($array_shell[0]);
$array_size = count($array_shell);

$i = 0;
$cofactor = array();

while($i < $array_size) {
$el_part_[$i] = $array_1[$i];
unset($el_part_[$i][0]);
$el_part_[$i] = array_values($el_part_[$i]);
array_push($cofactor, $el_part_[$i]);

++$i;
}

echo '<pre>',print_r($cofactor,1),'</pre>';

?>

My Question: How can I generalise this code to work for N sized arrays?

Baba · Accepted Answer · 2013-06-16 15:18:52Z

3

You don't need a complicated code .. Just loop and use array_shift

Example:

print_r(cleanUp($array_1));

Function

function cleanUp($array) {
    array_shift($array);
    foreach($array as $k => $var) {
        is_array($var) && array_shift($array[$k]);
    }
    return $array;
}

See Live DEMO

answered Jun 16, 2013 at 15:18

Baba

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Comments

geryjuhasz · Accepted Answer · 2013-06-16 15:24:28Z

1

$num = count($array_1);
for($i=0;$i<=$num;$i++)
{
if($i==0)
unset($array_1[$i]);
else unset($array_1[$i][0]);
}

answered Jun 16, 2013 at 15:24

geryjuhasz

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Comments

Ken Koch · Accepted Answer · 2013-06-16 15:25:05Z

1

Building off of Baba's answer, to work with N element arrays (assuming each array contains the same number of elements):

<?php
$array_1 = array(array(1,2,3,4), array(2,4,5,6), array(3,6,7,8));

$array = $array_1;
while(count($array[0]) > 2)
  $array = cleanUp($array);

print_r($array);

    function cleanUp($array) {
        array_shift($array);
        foreach($array as $k => $var) {
            is_array($var) && array_shift($array[$k]);
        }
        return $array;
    }

This will keep reducing until the sub-arrays have only 2 elements.

-Ken

answered Jun 16, 2013 at 15:25

Ken Koch

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