Grouping in array or a better way

[phppup]

I have an array of first and last names joined by an underscore (eg: Sally_Smith).

Ultimately, I want to count the number of people (elements) with the same last name.

My thinking is to run through the array and explode each element to isolate the last names, then use array_unique to create an array of $lastNameOnly and eventually use this as a counting mechanism against the original array..

Am I over-complicating this?

[mac_gyver]

if all you want is a COUNT() per last name, you can do that in the query that's getting the data, with a GROUP BY last_name term.

if you want the name data and a count for each last name, i would index/pivot the data using the last name as the main array index when you fetch the data, from wherever it is coming from.

[gizmola]

  On 4/9/2025 at 4:30 AM, mac_gyver said:

if all you want is a COUNT() per last name, you can do that in the query that's getting the data, with a GROUP BY last_name term.

if you want the name data and a count for each last name, i would index/pivot the data using the last name as the main array index when you fetch the data, from wherever it is coming from.

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From the way the question was worded, it doesn't appear that the data is in a relational database.

[phppup]

Correct. No database involved.

The array is generated from other PHP coding.

[mac_gyver]

  On 4/9/2025 at 4:30 AM, mac_gyver said:

if you want the name data and a count for each last name, i would index/pivot the data using the last name as the main array index when you -

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  On 4/9/2025 at 5:03 AM, phppup said:

generated (it) from other PHP coding.

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if you post the code generating the array, someone could post an example, instead of just writing about how to do it.

Edited April 9 by mac_gyver

[gizmola]

  On 4/9/2025 at 3:59 AM, phppup said:

I have an array of first and last names joined by an underscore (eg: Sally_Smith).

Ultimately, I want to count the number of people (elements) with the same last name.

My thinking is to run through the array and explode each element to isolate the last names, then use array_unique to create an array of $lastNameOnly and eventually use this as a counting mechanism against the original array..

Am I over-complicating this?

Expand  

To a degree, because you can create your desired list/count in one pass through the array.  

<?php

$names = ['bob_jones', 'sam_smith', 'jane_doe', 'john_smith', 'jill_jackson', 'matt_jones', 'john_doe', 'emily_smith'];
$lastNames = [];

foreach ($names as $name) {
    $lname = substr($name, strpos($name, '_') +1);
    if (array_key_exists($lname, $lastNames)) {
        $lastNames[$lname]++;
    } else {
        $lastNames[$lname] = 1;
    }
}

var_dump($lastNames);

 

[Barand]

$surname_counts = array_count_values(array_map(fn($v)=>substr($v, strpos($v, '_', 0)+1), $names));

->

Array
(
    [jones] => 2
    [smith] => 3
    [doe] => 2
    [jackson] => 1
)

 

[gizmola]

Hopefully, it's clear to you that Barand's solution and the one I presented are the same, only Barand used a 100% functional approach, and a lambda (anonymous function) passed to array_map.  

Compare/contrast the two solutions, and if you can understand them both, you'll have a good basis for solving future problems like this.

One thing I would note about these solutions, is that any solution is only as good as its suitability to the data.  For example, if the names can have suffixes like jr, sr, 3rd etc, you'll probably not get what you want.  They could be improved to handle those situations, should the data you're working with warrant it.

Using PHPUnit to create unit tests for code like this is a really valuable investment, if you care about testing, maintainability and quality.