php Optimize multiarray search - php

Question

I am reading in a file with thousands of lines. I grab the id from each line and check to see if it is in a multiarray, that also has thousands of entries. If it is in the multiarray I need to have the key of the array it is in. I have this all working with the code shown below but it takes a very long time. I'm hoping someone can suggest a way to do it faster?
$array = [['id' => 'A202977', '550' => 0, '710' => 0],
['id' => 'A202978', '550' => 0, '710' => 0],
['id' => 'A202979', '550' => 0, '710' => 0]
];
$found = InMultiArray('A202978', $array);
$key = MultiArraySearch('A202978', $array);
echo 'Found '.$found .' at '.$key.'<br>';
//shows Found 1 at 1
function InMultiArray($needle, $haystack, $strict = false) {
foreach ($haystack as $item) {
if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && InMultiArray($needle, $item, $strict))) {
return true;
}
}
return false;
}
function MultiArraySearch($needle, $haystack) {
foreach ($haystack as $key => $item) {
if (($needle == $item['id'])) {
return $key;
}
}
return FALSE;
}

Answer 1

You can safely and soundly cache the resulting resources into a JSON file, so next time when you need to load the data, you can just grab the content of the JSON file and pass it as a parameter to json_decode.
So, this is how you could proceed:
if the cached file does not exist or it is old, or it is older than the input file
proceed in the old and slow way
pass the result to json_encode and save it into a cache file
else
load the cache file's content
pass it as a parameter to json_decode and you have your result
Alternatively, you can use a database or even a cache-system, like Redis.

Answer 2

If you really need to find the index of the row by the ID field, you can create an associative array of IDs to array indices.
$array = [['id' => 'A202977', '550' => 0, '710' => 0],
['id' => 'A202978', '550' => 0, '710' => 0],
['id' => 'A202979', '550' => 0, '710' => 0]
];
// Array to map ID to array index in $dataRaw
$idIndexMap = [];
// Populate structs
foreach ($array as $i=>$currRow)
{
$idIndexMap[$currRow['id']] = $i;
}
$found = array_key_exists('A202978', $idIndexMap);
$key = $idIndexMap['A202978'];
echo 'Found ' . $found . ' at ' . $key . '<br>';
//shows Found 1 at 1
However if you just need to find the actual row by the ID, it's probably easier to just create an associative array that maps the ID to the actual row.
<?php
$array = [['id' => 'A202977', '550' => 0, '710' => 0],
['id' => 'A202978', '550' => 0, '710' => 0],
['id' => 'A202979', '550' => 0, '710' => 0]
];
// Array to map ID to array index in $dataRaw
$map = [];
// Populate structs
foreach ($array as $currRow)
{
$map[$currRow['id']] = $currRow;
}
$found = array_key_exists('A202978', $map);
$row = $map['A202978'];
echo 'Found ' . json_encode($row) . '<br>';