Finding value from another one in an array of arrays

Question

I got the follwing array and I would like to retrieve the name by the id:

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => john
        )
    [1] => Array
        (
            [id] => 2
            [name] => mark
        )
etc...

It is doable with double foreach loop and a conditional test, but is there a more elegant way?

A foreach is probably the quickest way of doing this as most other ways involve at least 1 pass of the entire array to convert it to a id => name array (unless you can generate this in the first place). — Nigel Ren
– Nigel Ren, Commented Feb 1, 2020 at 20:13

Tim Morton · Accepted Answer · 2020-02-01 20:18:12Z

2

Assuming that id is unique...

Long Version

$arr = [
    ['id'=1, 'name'='john'],
    ['id'=2, 'name'='mark'],
];

$lookup = [];
foreach($arr as $row) {
    $id = $row['id'];
    $name = $row['name'];
    $lookup[$id] = $name;
}

// find name for id, 2
echo $lookup[2];

// ==> mark

Short Version

...see Progrock’s solution!

answered Feb 1, 2020 at 20:18

Tim Morton

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Progrock · Accepted Answer · 2020-02-01 20:17:51Z

1

You can use array_column to map ids to names:

<?php

$arr = [
    ['id' => 1, 'name' => 'Rolf'],
    ['id' => 3, 'name' => 'Gary'],
    ['id' => 2, 'name' => 'Jimmy'],
];


$id_names = array_column($arr, 'name', 'id');

var_export($id_names);

print $id_names[3];

Output:

array (
  1 => 'Rolf',
  3 => 'Gary',
  2 => 'Jimmy',
)Gary

answered Feb 1, 2020 at 20:17

Progrock

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Finding value from another one in an array of arrays

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