Question

I have two arrays

ARRAY 1:

Array (
  [0] => Array (
    [fStartValidTime] => 2012-03-13
    [fMaxTemp] => 7
    [fMinTemp] => 2
  )
  [1] => Array (
    [fStartValidTime] => 2012-03-14
    [fMaxTemp] => 7
    [fMinTemp] => 5
  )
  [2] => Array (
    [fStartValidTime] => 2012-03-15
    [fMaxTemp] => 10
    [fMinTemp] => 5
  )
  [3] => Array (
    [fStartValidTime] => 2012-03-16
    [fMaxTemp] => 10
    [fMinTemp] => 1
  )
  [4] => Array (
    [fStartValidTime] => 2012-03-17
    [fMaxTemp] => 7
    [fMinTemp] => 3
  )
  [5] => Array (
    [fStartValidTime] => 2012-03-18
    [fMaxTemp] => 7
    [fMinTemp] => 3
  )
  [6] => Array (
    [fStartValidTime] => 2012-03-19
    [fMaxTemp] => 7
    [fMinTemp] => 1
  )
)

ARRAY 2:

Array (
  [2] => Array (
    [fStartValidTime] => 2012-03-13T16:00:00-7:00
    [fMaxTemp] => 6
    [fMinTemp] => 6
    [fWeatherType] => chancerain
    [fProbability] => likely
    [fCloudCoverPercent] => 20
  )
  [5] => Array (
    [fStartValidTime] => 2012-03-13T19:00:00-7:00
    [fMaxTemp] => 6
    [fMinTemp] => 6
    [fWeatherType] => chancerain
    [fProbability] => likely
    [fCloudCoverPercent] => 20
  )
  [8] => Array (
    [fStartValidTime] => 2012-03-13T22:00:00-7:00
    [fMaxTemp] => 5
    [fMinTemp] => 5
    [fWeatherType] => chancerain
    [fProbability] => likely
    [fCloudCoverPercent] => 20
  )
)

I want to switch the fMaxtTemp amd fMinTemp of Array2 to that of Array1 for just the first element of Array2. So

  [2] => Array (
    [fStartValidTime] => 2012-03-13T16:00:00-7:00
    [fMaxTemp] => 6
    [fMinTemp] => 6
    [fWeatherType] => chancerain
    [fProbability] => likely
    [fCloudCoverPercent] => 20
  )

will become

  [2] => Array (
    [fStartValidTime] => 2012-03-13T16:00:00-7:00
    [fMaxTemp] => 7
    [fMinTemp] => 2
    [fWeatherType] => chancerain
    [fProbability] => likely
    [fCloudCoverPercent] => 20
  )

Answer 1

Here is a simple solution:

NEW VERSION in response to DaveRandom’s comment:

<?php
$tmp = array_keys($array2);
$array2_first_idx = $tmp[0];
if ( count($array1) > 0 && count($array2) > 0 ) { // Prevent PHP Notice for empty arrays
    $array2[$array2_first_idx]['fMaxTemp'] = $array1[0]['fMaxTemp'];
    $array2[$array2_first_idx]['fMinTemp'] = $array1[0]['fMinTemp'];
}

ORIGINAL VERSION:

<?php
if ( count($array1) > 0 && count($array2) > 0 ) { // Prevent PHP Notice for empty arrays
    $array2['0']['fMaxTemp'] = $array1['0']['fMaxTemp'];
    $array2['0']['fMinTemp'] = $array1['0']['fMinTemp'];
}

Or, if you want to get fancy and replace as many keys in as many array positions as you want:

<?php
public function swap_array_values($a1, $a2, $pos, $keys)
{
    $tmp = $a2;

    foreach ($pos AS $idx) {
        // Make sure we have a value in the position we want to swap
        if ( array_key_exists($idx, $a1) && array_key_exists($idx, $a2) ) {
            foreach ($keys AS $key) {
                if ( array_key_exists($key, $a1[$idx]) && array_key_exists($key, $a2[$idx]) ) {
                    $tmp[$idx][$key] = $a1[$idx][$key];
                }
            }
        }
    }

    return $tmp;
}

// -------------------------------------------------------------------

$positions = array('0');
$swap_keys = array('fMaxTemp', 'fMinTemp');

echo "Before:<br/>";
echo "<strong>Array 1</strong><pre>"; print_r($array1); echo "</pre>";
echo "<strong>Array 2</strong><pre>"; print_r($array2); echo "</pre>";

$array2 = swap_array_values($array1, $array2, $positions, $swap_keys);

echo "<hr/>After:<br/>";
echo "<strong>Array 2</strong><pre>"; print_r($array2); echo "</pre>";