PHP - sort a multidimensional array by timestamp [duplicate] - php

Question

This question already has answers here:
How can I sort arrays and data in PHP?
(14 answers)
Closed 7 years ago.
I have been tried couple of times before asking here, i've also seen this question
which is similar to mine but unfortunatly it doesnt work (or i can get it working as well).
I have an array like this:
Array (
[user_1] => Array
(
[0] => Array
(
[category] => string_var
[time] => unix_timestamp
),
[1] => Array
(
[category] => string_var
[time] => unix_timestamp
),
[2] => Array
(
[category] => string_var
[time] => unix_timestamp
)
),
[user_2] => Array
(
[0] => Array
(
[category] => string_var
[time] => unix_timestamp
),
[1] => Array
(
[category] => string_var
[time] => unix_timestamp
),
[2] => Array
(
[category] => string_var
[time] => unix_timestamp
)
)
)
And for each user i have to sort the 2nd-level array by timestamp.
Hence, i've tried:
foreach ($array as $user => $user_data) {
timestamps = array();
foreach($user_data as $key => $actual_data) {
$timestamps[$key] = $actual_data['time'];
}
array_multisort($timestamps, SORT_ASC, $user_data);
}
unset($timestamps);
print_r($array); // the original array should now be sorted by timestamp
Well, no sorting happens, the final array is exactly = the original one.
NOTES :
the key ['time'] into the 2nd-level array comes from a MYSQL column
and it's stored as BIGINT. var_dump gives me: int(1432587949), so it shouldnt be a variable type issue
i have also tried usort, with the same result: no sorting.
Where am i wrong? thanks

Answer 1

You want to do something like this:
array_walk($array, function(&$arr) {usort($arr, function($a,$b){return ($a["time"] < $b["time"]) ? -1 : ($a["time"] > $b["time"] ? 1 : 0);});});
But since you said that the data come from a database then I suggest you sort them there because it's likely to be faster than sorting it in php.