Exception or error:
Array
(
[0] => Array
(
[dateTime] => 2011-10-18 0:0:00
[chanl1] => 20.7
[chanl2] => 45.4
[chanl3] =>
)
[1] => Array
(
[dateTime] => 2011-10-18 0:15:00
[chanl1] => 20.7
[chanl2] => 45.4
[chanl3] =>
)
[2] => Array
(
[dateTime] => 2011-10-18 00:14:00
[chanl1] => 20.7
[chanl2] => 33.8
[chanl3] =>
)
[3] => Array
(
[dateTime] => 2011-10-18 00:29:00
[chanl1] => 20.6
[chanl2] => 33.9
[chanl3] =>
)
I want to sort the above array based on the [dateTime], the final output should be:
Array
(
[0] => Array
(
[dateTime] => 2011-10-18 0:0:00
[chanl1] => 20.7
[chanl2] => 45.4
[chanl3] =>
)
[1] => Array
(
[dateTime] => 2011-10-18 00:14:00
[chanl1] => 20.7
[chanl2] => 33.8
[chanl3] =>
)
[2] => Array
(
[dateTime] => 2011-10-18 0:15:00
[chanl1] => 20.7
[chanl2] => 45.4
[chanl3] =>
)
[3] => Array
(
[dateTime] => 2011-10-18 00:29:00
[chanl1] => 20.6
[chanl2] => 33.9
[chanl3] =>
)
Is there anyone know how to do it? Thanks!
How to solve:
Use usort() function with custom comparator:
$arr = array(...);
usort($arr, function($a, $b) {
$ad = new DateTime($a['dateTime']);
$bd = new DateTime($b['dateTime']);
if ($ad == $bd) {
return 0;
}
return $ad < $bd ? -1 : 1;
});
DateTime class has overloaded comparison operators (<, >, ==).
Answer：
For performance, this method using array_multisort is very efficient:
$ord = array();
foreach ($array as $key => $value){
$ord[] = strtotime($value['dateTime']);
}
array_multisort($ord, SORT_ASC, $array);
print_r($array);
Answer：
Using uasort() with a custom sort callback should do it:
function cmp($a, $b) {
if ($a['dateTime'] == $b['dateTime']) {
return 0;
}
return ($a['dateTime'] < $b['dateTime']) ? -1 : 1;
}
uasort($arr, 'cmp');
uasort() preserves your array’s keys, you can use usort() instead if you don’t need that to happen.
Answer：
Use array_multisort :
<?php
$myarray=array(
0 => array
(
'dateTime' => '2011-10-18 00:0:00',
'chanl1' => '20.7',
'chanl2' => '45.4',
'chanl3' => '',
),
1 => array
(
'dateTime' => '2011-10-18 00:15:00',
'chanl1' => '20.7',
'chanl2' => '45.4',
'chanl3' => '',
),
2 => array
(
'dateTime' => '2011-10-18 00:14:00',
'chanl1' => '20.7',
'chanl2' => '33.8',
'chanl3' => '',
),
3 => array
(
'dateTime' => '2011-10-18 00:29:00',
'chanl1' => '20.6',
'chanl2' => '33.9',
'chanl3' => ''
));
foreach($myarray as $c=>$key) {
$dateTime[] = $key['dateTime'];
$chanl1[] = $key['chanl1'];
$chanl2[] = $key['chanl2'];
$chanl3[] = $key['chanl3'];
}
array_multisort($dateTime,SORT_ASC,SORT_STRING,$myarray);
print_r($myarray);
Answer：
For php array and object this example is helpful for sorting…
For datetime descending:
usort($response_data['callback'], function($a, $b) {
return strcasecmp(strtotime($b->view_date), strtotime($a->view_date));
});
For datetime ascending:
usort($response_data['callback'], function($a, $b) {
return strtotime($a->view_date) - strtotime($b->view_date);
});
Answer：
Simple sorting for DateTime objects with the spaceship operator:
$list = [
new DateTime('yesterday'),
new DateTime('today'),
new DateTime('1 week ago'),
];
uasort($list, function ($a, $b) {
return $a <=> $b;
});
var_dump($list);