Elegant way to convert associative array into an indexed one [duplicate] - php

Question

This question already has answers here:
Transposing multidimensional arrays in PHP
(12 answers)
Closed 1 year ago.
Having an associative array like
$myarray = array (
'user' => array (
2 => 'john',
5 => 'done',
21 => 'foo'
),
'city' => array (
2 => 'london',
5 => 'buenos aires',
21 => 'paris',
),
'age' => array (
2 => 24,
5 => 38,
21 => 16
)
...
);
EDITED
Assuming I don't know how many keys this array has, nor the keys themselves (they could be whatever) The above is just an example
Is there any elegant way (using built-in functions and not loops) to convert it into
$result = array(
array(
'user',
'city',
'age'
...
),
array(
'john',
'london',
24
...
),
array(
'done',
'buenos aires',
38
...
),
array(
'foo',
'paris',
16
...
)
);
As a side question: how to obtain this too (in a similar elegant way)
$result = array(
array(
'row',
'user',
'city',
'age'
...
),
array(
2,
'john',
'london',
24
...
),
array(
5,
'done',
'buenos aires',
38
...
),
array(
21,
'foo',
'paris',
16
...
)
);

Answer 1

Note that both of these operations are basically the transpose of your original array.
All of this is strongly adapted from this answer (consider upvoting it!).
helper
First we need a helper function, which keeps the row headers as the keys in the associative array:
function flipArrayKeys($arr) {
$out = array('row' => array_keys($arr));
foreach ($arr as $key => $subarr) {
foreach ($subarr as $subkey => $subvalue) {
$out[$subkey][] = $subvalue;
}
}
return $out;
}
flipArrayKeys($myarray) gives:
array (
'row' =>
array (
0 => 'user',
1 => 'city',
2 => 'age',
),
2 =>
array (
0 => 'john',
1 => 'london',
2 => 24,
),
5 =>
array (
0 => 'done',
1 => 'buenos aires',
2 => 38,
),
21 =>
array (
0 => 'foo',
1 => 'paris',
2 => 16,
),
)
part 1
$result = array_values(flipArrayKeys($myarray));
and now result looks like:
array (
0 =>
array (
0 => 'user',
1 => 'city',
2 => 'age',
),
1 =>
array (
0 => 'john',
1 => 'london',
2 => 24,
),
2 =>
array (
0 => 'done',
1 => 'buenos aires',
2 => 38,
),
3 =>
array (
0 => 'foo',
1 => 'paris',
2 => 16,
),
)
This part can also be done using transpose from this answer:
$result = transpose($myarray);
array_unshift($result, array_keys($myarray));
part 2
function flipArrayWithHeadings($arr) {
$out = flipArrayKeys($arr);
foreach (array_keys($out) as $key) {
array_unshift($out[$key],$key);
}
return array_values($out);
}
So flipArrayWithHeadings($myarray) looks like:
array (
0 =>
array (
0 => 'row',
1 => 'user',
2 => 'city',
3 => 'age',
),
1 =>
array (
0 => 2,
1 => 'john',
2 => 'london',
3 => 24,
),
2 =>
array (
0 => 5,
1 => 'done',
2 => 'buenos aires',
3 => 38,
),
3 =>
array (
0 => 21,
1 => 'foo',
2 => 'paris',
3 => 16,
),
)

Answer 2

Use the array_values function as:
$result = array(array_values($myarray['user']),
array_values($myarray['city']),
array_values($myarray['age']));
For the 2nd part of the question you can do:
$result2 = array_keys($myarray);
foreach(array_keys($myarray['user']) as $k) {
$result2[] = array($k, $myarray['user'][$k], $myarray['city'][$k], $myarray['age'][$k]);
}