Merge arrays inside array dynamically which have the same keys - php

Question

I am using PHP 5.6. I have an array like this:
$array = [
0 => [
'johndrake#gmail.com' => [
'email' => 'johndrake#gmail.com',
'firstname' => 'john',
'lastname' => 'drake',
'food' => 'burger',
],
],
1 => [
'johndrake#gmail.com' => [
'email' => 'johndrake#gmail.com',
'firstname' => 'john',
'lastname' => 'drake',
'drink' => 'coke',
],
],
2 => [
'samwin#gmail.com' => [
'email' => 'samwin#gmail.com',
'firstname' => 'sam',
'lastname' => 'win',
'food' => 'pizza',
],
],
3 => [
'samwin#gmail.com' => [
'email' => 'samwin#gmail.com',
'firstname' => 'sam',
'lastname' => 'win',
'drink' => 'pepsi',
],
],
];
Let's say that "food" and "drink" are categories and they can differ depending on how the questionnaire was setup. So there could in fact be "food", "drink", and "dessert" for example. As you can see, there is an array for each person, for each category. What I would like to do is to merge the arrays by each person so that it will instead show up with the following:
$array = [
0 => [
'johndrake#gmail.com' => [
'email' => 'johndrake#gmail.com',
'firstname' => 'john',
'lastname' => 'drake',
'food' => 'burger',
'drink' => 'coke', // Merged
],
],
1 => [
'samwin#gmail.com' => [
'email' => 'samwin#gmail.com',
'firstname' => 'sam',
'lastname' => 'win',
'food' => 'pizza',
'drink' => 'pepsi', // Merged
],
],
];
I have looked at array_merge as well as array_merge_recursive, however from everything that I've read, you have to specify the arrays in order to merge them, for example it has to be array_merge(array[0], array[1]). As you can see, I can't exactly do this because there could be 2,3 or even 4 arrays per person which have to be merged together.
So how do I dynamically merge the arrays for each person so that it shows all their information together?

Answer 1

This is not exactly as the result you asked for and it feels pretty messy, but it might be something you can work further with :)
$result = [];
foreach ($array as $answers) {
foreach ($answers as $email => $values) {
if (!isset($result[$email])) {
$result[$email] = $values;
continue;
}
$result[$email] = array_merge($result[$email], $values);
}
}
And the result:
$result === [
'johndrake#gmail.com' => [
'email' => 'johndrake#gmail.com',
'firstname' => 'john',
'lastname' => 'drake',
'food' => 'burger',
'drink' => 'coke',
],
'samwin#gmail.com' => [
'email' => 'samwin#gmail.com',
'firstname' => 'sam',
'lastname' => 'win',
'food' => 'pizza',
'drink' => 'pepsi',
],
]

Answer 2

<?php
$originalArray=array (
0 => array ('johndrake#gmail.com' => array ('email' => 'johndrake#gmail.com', 'firstname' => 'john', 'lastname' => 'drake', 'food' => 'burger')),
1 => array ('johndrake#gmail.com' => array ('email' => 'johndrake#gmail.com', 'firstname' => 'john', 'lastname' => 'drake', 'drink' => 'coke')),
2 => array ('samwin#gmail.com' => array ('email' => 'samwin#gmail.com', 'firstname' => 'sam', 'lastname' => 'win', 'food' => 'pizza')),
3 => array ('samwin#gmail.com' => array ('email' => 'samwin#gmail.com', 'firstname' => 'sam' ,'lastname' => 'win', 'drink' => 'pepsi'))
);
$tempArray=array();
$newArray=array();
foreach($originalArray as $key=>$val){
$valKey=key($val);
if(isset($tempArray[$valKey])){
$newArray[]=array_merge($tempArray[$valKey],$val[$valKey]);
}
else{
$tempArray[$valKey]=$val[$valKey];
}
}
echo "<pre>";print_r($newArray);