CODEWITHSUNDEEP
phparraysgroupingpreserve
Jan Ariel San Jose
Jan Ariel San Jose

Reputation: 720

Group associative array elements by values and preserve original keys as new values in each group

I want to be able to group Associative Arrays with their `keys. So far I'm lost of what syntax to use.

As of now, I have thus code,

$associativeArray = array("Ripe Mango"=>"Yellow", "Strawberry"=>"Red", "Lemon"=>"Yellow");
groupByColor($associativeArray);

function groupByColor($groupedArray)
{
  return $groupedArray;
}

My goal is to return the array while having it grouped, the ideal result will be like this;

["Yellow"=>["Ripe Mango", "Lemon"], "Red"=>["Strawberry"]]

Any hints on what method to use?

Upvotes: 2

Views: 2196

Answers (6)

Death-is-the-real-truth
Death-is-the-real-truth

Reputation: 72269

Inside function do foreach()

<?php

$associativeArray = array("Ripe Mango" => "Yellow", "Strawberry" => "Red", "Lemon" => "Yellow");

function groupByColor($associativeArray) {
    $final_array = [];
    foreach ($associativeArray as $key => $val) {
        $final_array[$val][] = $key;
    }
    
    return $final_array;  
}
print_r(groupByColor($associativeArray));

Note:- you can assign groupByColor($associativeArray) returned array to a new variable and print that variable like below:-

$color_array = groupByColor($associativeArray);
print_r($color_array);

Upvotes: 3

mickmackusa
mickmackusa

Reputation: 48001

This task can be elegantly performed with a body-less foreach loop.

In the loop signature, declare the values as $v, then use square brace syntax to push elements into their appropriate groups. The first level is identified by the declared $v value and the "original key" will be pushed as a new entry into the group's indexed subarray.

Code: (Demo)

$array = [
    "Ripe Mango" => "Yellow",
    "Strawberry" => "Red",
    "Lemon" => "Yellow"
];
$result = [];

foreach ($array as $result[$v][] => $v);

var_export($result);

Using functional iteration just doesn't have the same elegance. (Demo)

var_export(
    array_reduce(
        array_keys($array),
        fn($result, $key) => array_merge_recursive($result, [$array[$key] => [$key]]),
        []
    )
);

Upvotes: 0

Gaurav Kandpal
Gaurav Kandpal

Reputation: 1330

Only way I know how to do it would be with a loop.

<!DOCTYPE html>
<html>
<body>

<?php
$associativeArray = array("Ripe Mango"=>"Yellow", "Strawberry"=>"Red", "Lemon"=>"Yellow");

$data = groupByColor($associativeArray);
print_r($data);

function groupByColor($groupedArray)
{
    foreach ($groupedArray as $key => $value) {
        $final[$value][] = $key;
     } 

    return $final;
}
?>

</body>
</html>

Upvotes: 0

T. AKROUT
T. AKROUT

Reputation: 1715

You can use array_walk function to trait every value of the array:

<?php
$array = ["Ripe Mango"=>"Yellow", "Strawberry"=>"Red", "Lemon"=>"Yellow"];
$result = [];
array_walk($array, function ($value, $key) use (&$result) {
    $result[$value][] = $key;
});

print_r($result);

Upvotes: 1

user8034901
user8034901

Reputation:

foreach() through your array and add to a new array with the color as key:

<?php
$associativeArray = array("Ripe Mango"=>"Yellow", "Strawberry"=>"Red", "Lemon"=>"Yellow");
$new = groupByColor($associativeArray);
var_dump($new);

function groupByColor($groupedArray)
{
    foreach ( $groupedArray as $key => $color ) {
        $tmp[$color][] = $key;
    }
    return $tmp;
}

Upvotes: 0

Nitin Goyal
Nitin Goyal

Reputation: 507

You can do this by processing each key and convert value to key and check if exist then append to it else create it

function groupByColor ($groupedArray) {
  $result = array();
  foreach ($groupedArray as $key=>$val) {
    if (array_key_exists($val, $result)) {
      $result[$val][] = $key;
    } else {
      $result[$val] = array();
    }
  }
  return $result;
}

Upvotes: 0

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