Get flat array of values from a specified column of a 2d array [duplicate]

Question

I have an array that contains 4 arrays with one value each.

array(4) {
  [0]=>
  array(1) {
    ["email"]=>
    string(19) "[email protected]"
  }
  [1]=>
  array(1) {
    ["email"]=>
    string(19) "[email protected]"
  }
  [2]=>
  array(1) {
    ["email"]=>
    string(19) "[email protected]"
  }
  [3]=>
  array(1) {
    ["email"]=>
    string(19) "[email protected]"
  }
}

What is the best (=shortest, native PHP functions preferred) way to flatten the array so that it just contains the email addresses as values:

array(4) {
  [0]=>
  string(19) "[email protected]"
  [1]=>
  string(19) "[email protected]"
  [2]=>
  string(19) "[email protected]"
  [3]=>
  string(19) "[email protected]"
}

moonwave99 · Accepted Answer · 2014-04-08 16:06:47Z

21

In PHP 5.5 you have array_column:

$plucked = array_column($yourArray, 'email');

Otherwise, go with array_map:

$plucked = array_map(function($item){ return $item['email'];}, $yourArray);

answered Apr 8, 2014 at 16:06

moonwave99

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2 Comments

Populus Over a year ago

Or if you don't have PHP 5.5, you can use the userland implementation of array_column github.com/ramsey/array_column by the author of the official function

Marcin Orlowski Over a year ago

Since PHP 7.4 you can use arrow function to make it more compact: $plucked = array_map(static fn($item) => $item['email'], $yourArray);

Shankar Narayana Damodaran · Accepted Answer · 2014-04-08 16:24:16Z

2

You can use a RecursiveArrayIterator . This can flatten up even multi-nested arrays.

<?php
$arr1=array(0=> array("email"=>"[email protected]"),1=>array("email"=>"[email protected]"),2=> array("email"=>"[email protected]"),
    3=>array("email"=>"[email protected]"));
echo "<pre>";
$iter = new RecursiveIteratorIterator(new RecursiveArrayIterator($arr1));
$new_arr = array();
foreach($iter as $v) {
    $new_arr[]=$v;
}
print_r($new_arr);

OUTPUT:

Array
(
    [0] => [email protected]
    [1] => [email protected]
    [2] => [email protected]
    [3] => [email protected]
)

edited Apr 8, 2014 at 16:24

answered Apr 8, 2014 at 16:04

Shankar Narayana Damodaran

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2 Comments

dialogik Over a year ago

Also nice approach, but I prefer @moonwave99's answer as it is a lean one liner.

Shankar Narayana Damodaran Over a year ago

@GottliebNotschnabel, No problem. I suggested this as a generalized solution as this will work even on multidimensional arrays.

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