array_count_values for Specific Keys in Associative Array

Question

Let's say I have an array like this:

Array
(
    [id] => 1
    [color_object] => blue
    [color_1] => green
    [color_2] => blue
    [color_3] => blue
    [color_4] => red
    [color_5] => purple
    [AltColor] => blue
)

I can use array_count_values and it will give me the count for blue as 4.

But I need to only count the values within specific keys of the array, in this example I need to limit my count to the color_1 color_2 color_3 color_4 and color_5 only.

Is it possible to only count the instances of blue within specified keys, giving me a desired result of 2?

PHP code:

$array = array("id"=>"1", "color_object"=>"blue", "color_1"=>"green", "color_2"=>"blue", "color_3"=>"blue", "color_4"=>"red", "color_5"=>"purple", "AltColor"=>"blue");

Why do you have separate color_1, color_2, etc. elements? Why not make it an array 'colors' => array('green', 'blue', 'blue', 'red', 'purple', 'blue') — Barmar
– Barmar, Commented Dec 15, 2016 at 3:09
In general, whenever you find yourself creating numbered variables or keys like that, you should probably be using an array instead. — Barmar
– Barmar, Commented Dec 15, 2016 at 3:11
The actual array I am working with is one returned from mysqli_fetch_assoc. I was trying to minimize the question, and I don't think I have as much control over the array as my question implied. Can you suggest a function reference to look into? I think maybe creating another array with just those keys might work in this instance. — bbruman
– bbruman, Commented Dec 15, 2016 at 3:16
I just supplied the manually created PHP code so I could provide a code example to work with. — bbruman
– bbruman, Commented Dec 15, 2016 at 3:17

YaHui Jiang · Accepted Answer · 2016-12-15 03:39:39Z

2

<?php

    $array = array(
        "id"=>"1",
        "color_object"=>"blue",
        "color_1"=>"green",
        "color_2"=>"blue",
        "color_3"=>"blue",
        "color_4"=>"red",
        "color_5"=>"purple",
        "AltColor"=>"blue"
    );

    $preg = '/^color_\d{1,}/i';

    $callback = function ($val) use($preg) {
        if (preg_match($preg, $val, $match)) {
            return true;
        } else {
            return false;
        }   
    };

    $data = array_filter($array, $callback, ARRAY_FILTER_USE_KEY);
    $result = array_count_values($data);

    var_dump($result);

answered Dec 15, 2016 at 3:39

YaHui Jiang

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3 Comments

YaHui Jiang Over a year ago

array_filter($array, $callback, ARRAY_FILTER_USE_KEY); ARRAY_FILTER_USE_KEY php version >= 5.6

bbruman Over a year ago

Thank you! I'm still maybe looking for something simpler, though. Going to have to do some more research and work on this tomorrow I will accept an answer then.

bbruman Over a year ago

Actual solution I used is in the comments of my original post, but I'm going to accept your answer as you were the first to provide a solution to the broader question.

Beginner · Accepted Answer · 2016-12-15 04:50:01Z

1

You can just use function array_sum wrap your array_map inside it to add just return indexes that meet your condition

$array = Array
(
    'id' => 1,
    'color_code' => 'blue',
    'color_1' => 'green',
    'color_2' => 'blue',
    'color_3' => 'blue',
    'color_4' => 'red',
    'color_25' => 'purple',
    'AltColor' => 'blue',
);

echo "The total count is of index => color and value => blue is ".array_sum(array_map(
    function($value, $key) {
        return (preg_match('/^color_\d{1,}/i', $key) && $value == 'blue') ? true : false;
    }, $array, array_keys($array))
);

Demo

edited Dec 15, 2016 at 4:50

answered Dec 15, 2016 at 3:39

Beginner

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