PHP - How do I partially compare elements in 2 arrays - php

Question

I have 2 arrays:
$arr1 = array('Test', 'Hello', 'World', 'Foo', 'Bar1', 'Bar'); and
$arr2 = array('hello', 'Else', 'World', 'Tes', 'foo', 'BaR1', 'Bar');
I need to compare the 2 arrays and save the position of the matching elements to a 3rd array $arr3 = (3, 0, 2, 4, 5, 6); //expected result, displaying position of matching element of $arr1 in $arr2.
By 'matching' I mean all elements that are identical (ex. World), or partially the same (ex. Test & Tes) and also those elements that are alike but are in different case (ex. Foo & foo, Bar & bar).
I've tried a series of combinations and of various functions without success, using functions like array_intersect(), substr_compare(), array_filter() and more. I'm not asking for the exact solution, just something to get me on the right track because i'm going around in circles all afternoon.

Answer 1

This seemed to work for me, but I'm sure there are some edge cases I'm missing that you'd need to test for:
foreach( $arr1 as $i => $val1) {
$result = null;
// Search the second array for an exact match, if found
if( ($found = array_search( $val1, $arr2, true)) !== false) {
$result = $found;
} else {
// Otherwise, see if we can find a case-insensitive matching string where the element from $arr2 is at the 0th location in the one from $arr1
foreach( $arr2 as $j => $val2) {
if( stripos( $val1, $val2) === 0) {
$result = $j;
break;
}
}
}
$arr3[$i] = $result;
}
It produces your desired output array:
Array ( [0] => 3 [1] => 0 [2] => 2 [3] => 4 [4] => 5 [5] => 6 )

Answer 2

Try array_uintersect() with a callback function that implements your "matching" algorithm.

Answer 3

Looks like you need 2 foreach loops, and stripos (or mb_stripos for Unicode) for comparing.

Answer 4

I came up with this to account for duplicates. It returns both keys and both values so you can compare to see if it's working properly. To refine it, you can just comment out the lines setting the values you don't need. It matches all cases.
<?php
$arr1 = array('Test', 'Hello', 'World', 'Foo', 'Bar1', 'Bar');
$arr2 = array('hello', 'Else', 'World', 'Tes', 'foo', 'BaR1', 'Bar');
$matches = array();
//setup the var for the initial match
$x=0;
foreach($arr1 as $key=>$value){
$searchPhrase = '!'.$value.'!i';
//Setup the var for submatching (in case there is more than one)
$y=0;
foreach($arr2 as $key2=>$value2){
if(preg_match($searchPhrase,$value2)){
$matches[$x][$y]['key1']=$key;
$matches[$x][$y]['key2']=$key2;
$matches[$x][$y]['arr1']=$value;
$matches[$x][$y]['arr2']=$value2;
}
$y++;
}
unset($y);
$x++;
}
print_r($matches);
?>
Output looks like this:
Array
(
[1] => Array
(
[0] => Array
(
[key1] => 1
[key2] => 0
[arr1] => Hello
[arr2] => hello
)
)
[2] => Array
(
[2] => Array
(
[key1] => 2
[key2] => 2
[arr1] => World
[arr2] => World
)
)
[3] => Array
(
[4] => Array
(
[key1] => 3
[key2] => 4
[arr1] => Foo
[arr2] => foo
)
)
[4] => Array
(
[5] => Array
(
[key1] => 4
[key2] => 5
[arr1] => Bar1
[arr2] => BaR1
)
)
[5] => Array
(
[5] => Array
(
[key1] => 5
[key2] => 5
[arr1] => Bar
[arr2] => BaR1
)
[6] => Array
(
[key1] => 5
[key2] => 6
[arr1] => Bar
[arr2] => Bar
)
)
)