How to reference cells with specific condition in php multidimensional array - php

Question

I got an array like this:
$array[0][name] = "Axel";
$array[0][car] = "Pratzner";
$array[0][color] = "black";
$array[1][name] = "John";
$array[1][car] = "BMW";
$array[1][color] = "black";
$array[2][name] = "Peggy";
$array[2][car] = "VW";
$array[2][color] = "white";
I would like to do something like "get all names WHERE car = bmw AND color = white"
Could anyone give advice on how the PHP spell would look like?

Answer 1

function getWhiteBMWs($array) {
$result = array();
foreach ($array as $entry) {
if ($entry['car'] == 'bmw' && $entry['color'] == 'white')
$result[] = $entry;
}
return $result;
}
Edited: This is a more general solution:
// Filter an array using the given filter array
function multiFilter($array, $filters) {
$result = $array;
// Removes entries that don't pass the filter
$fn = function($entry, $index, $filter) {
$key = $filter['key'];
$value = $filter['value'];
$result = &$filter['array'];
if ($entry[$key] != $value)
unset($result[$index]);
};
foreach ($filters as $key => $value) {
// Pack the filter data to be passed into array_walk
$filter = array('key' => $key, 'value' => $value, 'array' => &$result);
// For every entry, run the function $fn and pass in the filter data
array_walk($result, $fn, $filter);
}
return array_values($result);
}
// Build a filter array - an entry passes this filter if every
// key in this array corresponds to the same value in the entry.
$filter = array('car' => 'BMW', 'color' => 'white');
// multiFilter searches $array, returning a result array that contains
// only the entries that pass the filter. In this case, only entries
// where $entry['car'] = 'BMW' AND $entry['color'] = 'white' will be
// returned.
$whiteBMWs = multiFilter($array, $filter);

Answer 2

Doing this in code is more or less emulating what a RDBMS is perfect for. Something like this would work:
function getNamesByCarAndColor($array,$color,$car) {
$matches = array();
foreach ($array as $entry) {
if($entry["color"]== $color && $entry["car"]==$car)
matches[] = $entry["name"];
}
return $matches;
}
This code would work well for smaller arrays, but as they got larger and larger it would be obvious that this isn't a great solution and an indexed solution would be much cleaner.