How to Efficiently Compare Nested Associative Arrays for Differences?

Comparing Nested Associative Arrays for Differences

In the context of programming, when dealing with multi-dimensional associative arrays, it often becomes necessary to compare their contents and identify differences. Consider the scenario where you have two arrays:

$pageids = [
    ['id' => 1, 'linklabel' => 'Home', 'url' => 'home'],
    ['id' => 2, 'linklabel' => 'Graphic Design', 'url' => 'graphicdesign'],
    ['id' => 3, 'linklabel' => 'Other Design', 'url' => 'otherdesign'],
    ['id' => 6, 'linklabel' => 'Logo Design', 'url' => 'logodesign'],
    ['id' => 15, 'linklabel' => 'Content Writing', 'url' => 'contentwriting'],
];

$parentpage = [
    ['id' => 2, 'linklabel' => 'Graphic Design', 'url' => 'graphicdesign'],
    ['id' => 3, 'linklabel' => 'Other Design', 'url' => 'otherdesign'],
];

The goal is to find the rows in $pageids that are not present in $parentpage. Using array_diff_assoc() alone may not yield the desired result if the arrays contain nested associative arrays. To address this issue, we can leverage array_map() and unserialize().

$pageWithNoChildren = array_map('unserialize',
    array_diff(array_map('serialize', $pageids), array_map('serialize', $parentpage)));

First, array_map() iterates over the sub-arrays in both $pageids and $parentpage and serializes each sub-array into a string representation using serialize(). This effectively converts the multi-dimensional arrays into one-dimensional arrays with strings as elements.

Next, array_diff() compares the string representations of the sub-arrays and returns an array containing only the differences. The resulting array is then passed back to array_map(), which iterates over each string and unserializes it back into its original sub-array representation using unserialize().

As a result, $pageWithNoChildren will contain an array of sub-arrays that represent the rows in $pageids that are not present in $parentpage. This approach effectively compares the contents of the nested associative arrays and provides the desired differences.

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