Changing values in array based on values in another array

Question

Here's an example in plain english of what I am trying to achieve: if the number given is 4, then I want to add 1 to every value that is equal to or less than 4 into the corresponding index of another array. (hope that makes sense)

So my first array looks like this:

Array ( [0] => 5 [1] => 6 [2] => 7 [3] => 4 [4] => 3 [5] => 2 [6] => 9 [7] => 8 [8] => 1 [9] => 10 [10] => 11 [11] => 12 [12] => 13 [13] => 14 [14] => 15 [15] => 16 [16] => 17 [17] => 18 )

The second array looks like this:

Array ( [0] => 4 [1] => 3 [2] => 4 [3] => 4 [4] => 4 [5] => 5 [6] => 4 [7] => 4 [8] => 5 [9] => 4 [10] => 4 [11] => 5 [12] => 5 [13] => 4 [14] => 4 [15] => 4 [16] => 3 [17] => 3 )

And I am wanting the second array to look like this (after adding 1 to every value below 4 in the first array) so after the addition it would be

Array ( [0] => 4 [1] => 3 [2] => 4 [3] => 5 [4] => 5 [5] => 6 [6] => 4 [7] => 4 [8] => 6 [9] => 4 [10] => 4 [11] => 5 [12] => 5 [13] => 4 [14] => 4 [15] => 4 [16] => 3 [17] => 3 )

In which index 3,4,5,9 have changed.

How is the first array used in all of this? Shouldn't index 8 (instead of 9) be updated? — Ja͢ck
– Ja͢ck, Commented Mar 28, 2014 at 6:31

Radu Diță · Accepted Answer · 2014-03-28 06:27:41Z

3

I think you're looking for array_map

function increase( $m, $n )
{
  if( $m < 4 )
  {
   return $n+1;
  }
  return $n
}

$arr1;
$arr2;

print_r( array_map("increase", $arr1, $arr2 ) );

Note: this will return a new array.

answered Mar 28, 2014 at 6:27

Radu Diță

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Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Using an array_walk

array_walk($arr2,function(&$v,$k) use($arr1) { if($arr1[$k]<=$v){ $v=$v+1;} });

Demo

[or]

A simple foreach will do

foreach($arr1 as $k=>$v)
{
    if($v<=$arr2[$k])
    {
        $arr2[$k]=$arr2[$k]+1;
    }
}
print_r($arr2);

Demo

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Mar 28, 2014 at 6:26

Shankar Narayana Damodaran

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