array_diff on array of associative arrays in php

Asked 1 Year ago Answers: 5 Viewed 24 times

I have two arrays of the form

Array1: [0]=> Array([name] => foo [id] => 12) [1]=> Array([name] => bar [id] => 34)
Array2: [0]=>Array([name] => bar [id]=> 34) [1]=>Array([name] => baz [id]=> 56)

The arrays come from a database and any two pairs can have the same name but ID's are unique. I am trying to compare the arrays by ID likes so:

$one_not_two = array_diff($array1[id], $array2[id]);
but that does not return anything. I also tried
$one_not_two = array_diff($array1[id], $array2[id]);
which returned an error "argument is not an array." Originally I got around it by extracting the IDs into a one-dimensional array and just comparing those but now a new feature requires me to compare the pairs. Any advice?

PS Our servers are running php 5.3 if that makes any difference.

Answers

Because the arrays are multidimensional you have to extract the ids like this:

$ids1 = array();
foreach($array1 as $elem1)
    $ids1[] = $elem1['id'];

$ids2 = array();
foreach($array2 as $elem2)
    $ids2[] = $elem2['id'];

$one_not_two = array_diff($ids1,$ids2);

For your specific question, check out array_diff() with multidimensional arrays

Saturday, May 29, 2021

etsous

Yes, you may trust it. All ways of interpolation a variable are covered in the documentation pretty well.

If you want to have a reason why this was done so, well, I can't help you there. But as always: PHP is old and has evolved a lot, thus introducing inconsistent syntax.

Thursday, April 1, 2021

Kemrop

You can sort a collection with sort methods by a given key:

$sorted = $collection->sortByDesc('status');

Thursday, April 1, 2021

DCD

What about this:

function convert($array) {
    return (count($array) === 0) ? "" : $array;
}

$empty_array = array();
$empty_array = convert($empty_array);

This will simply convert it into a empty string if the array is empty.

An object is somewhat more complicated but you can just use get_object_vars():

function convert($object) {
    return (count(get_object_vars($object)) === 0) ? "" : $object;
}

Nb.: You cannot check an object on private variables.

Thursday, April 1, 2021

PHLAK

Use the indexes of one of the sub-arrays to access all the other sub-arrays:

foreach ($array['item_id'] as $i => $item_id) {
    $request_explanation = $array['request_explanation'][$i];
    $quantity = $array['quantity'][$i];
    // repeat this for all the columns
    // Now you can insert all these variables into the database
}

Saturday, May 29, 2021

Dail

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array_diff on array of associative arrays in php

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