CODEWITHSUNDEEP
phparraysmultidimensional-arraygroupingsub-array
user1125394
user1125394

Reputation:

Group rows of a 2d array by a column and create separate arrays

I would like to split an array:

$o = json_decode('[{"id":"1","color":"green"},{"id":"2","color":"green"},{"id":"3","color":"yellow"},{"id":"4","color":"green"}]');

based on the color attribute of each item, and fill corresponding sub arrays

$a = array("green", "yellow", "blue");

function isGreen($var) {
    return ($var->color == "green");
}

$greens = array_filter($o, "isGreen");
$yellows = array_filter($o, "isYellow");
// and all possible categories in $a..

My $a has a length > 20, and could increase more, so I need a dynamic way instead of writing functions by hand.

There doesn't seem to exist a function array_split() to generate all filtered arrays
or else I might need a kind of lambda function.

Upvotes: 4

Views: 649

Answers (3)

hovado
hovado

Reputation: 4948

If you need more arguments you could use this function:

function splitArray($array, $params) {
    $result = array();

    foreach ($array as $item) {

        $status = true;

        foreach ($params as $key => $value) {
            if ($item[$key] != $value) {
                $status = false;
                continue;
            }
        }

        if ($status == true) {
            $result[] = $item;
        }
    }

    return $result;
}

$greensAndID1 = splitArray($o, array('color' => 'green', 'id' => 1));

Upvotes: 0

PeeHaa
PeeHaa

Reputation: 72672

You could do something like:

$o = json_decode('[{"id":"1","color":"green"},{"id":"2","color":"green"},{"id":"3","color":"yellow"},{"id":"4","color":"green"}]');

$greens = array_filter($o, function($item) {
    if ($item->color == 'green') {
        return true;
    }

    return false;
});

Or if you want to create something really generic you could do something like the following:

function filterArray($array, $type, $value)
{
    $result = array();
    foreach($array as $item) {
        if ($item->{$type} == $value) {
            $result[] = $item;
        }
    }

    return $result;
}

$o = json_decode('[{"id":"1","color":"green"},{"id":"2","color":"green"},{"id":"3","color":"yellow"},{"id":"4","color":"green"}]');
$greens = filterArray($o, 'color', 'green');
$yellows = filterArray($o, 'color', 'yellow');

In my second example you could just pass the array and tell the function what to filter (e.g. color or some other future property) on based on what value.

Note that I have not done any error checking whether properties really exist

Upvotes: 6

simshaun
simshaun

Reputation: 21466

I would not go down the road of creating a ton of functions, manually or dynamically.

Here's my idea, and the design could be modified so filters are chainable:

<?php
class ItemsFilter
{
    protected $items = array();

    public function __construct($items) {
        $this->items = $items;
    }

    public function byColor($color)
    {
        $items = array();

        foreach ($this->items as $item) {
            // I don't like this: I would prefer each item was an object and had getColor()
            if (empty($item->color) || $item->color != $color)
                continue;

            $items[] = $item;
        }

        return $items;
    }
}

$items = json_decode('[{"id":"1","color":"green"},{"id":"2","color":"green"},{"id":"3","color":"yellow"},{"id":"4","color":"green"}]');
$filter = new ItemsFilter($items);
$greens = $filter->byColor('green');

echo '<pre>';
print_r($greens);
echo '</pre>';

Upvotes: 1

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