Fastest way to process this array using PHP

Question

I am looking to go from:

array($ID => array (name => $name, created => $timestamp))

e.g

[5632][name] = martin
[5632][created] = 131232342
[6742][name] = paul
[6742][created] = 131232312
[6321][name] = peter
[6321][created] = 131232311

to an array of ids ordered by creation like

[0] = 6321
[1] = 6742
[2] = 5632

What is the fastest way to achieve such in PHP?

It does, however due to the complexity of the query I store the data in the users session when they login to my app. — Pablo
– Pablo, Commented Aug 24, 2010 at 17:55

Daniel Vandersluis · Accepted Answer · 2010-08-24 16:26:20Z

3

function sort_by_date($a, $b)
{
  if ($a['created'] == $b['created']) return 0;
  return ($a['created'] < $b['created']) ? -1 : 1;
}

$array = array(...);
uasort($array, "sort_by_date");
$ids = array_keys($array);

uasort lets you sort an array by using a custom function while maintaining keys. array_keys returns an array containing the keys of another array.

answered Aug 24, 2010 at 16:26

Daniel Vandersluis

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3 Comments

Pablo Over a year ago

would this be any faster function sort_by_date($a, $b) { return strnatcmp($a['created'], $b['created']); }

Daniel Vandersluis Over a year ago

You could benchmark it, but my guess would be that strnatcmp would be slower (especially if your created keys are already numbers)

Pablo Over a year ago

You were correct. Your script managed 1 million iterations in 7 seconds on my server where as strnatcmp took around 9.

salathe · Accepted Answer · 2010-08-24 18:41:51Z

1

Why go through the effort of sorting the entire array of arrays, when you just want the ids?

$times = array();
foreach ($array as $key => $item) {
    $times[$key] = $item['created'];
}
asort($times);
$ids = array_keys($times);

answered Aug 24, 2010 at 18:41

salathe

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Comments

Alex Pliutau · Accepted Answer · 2010-08-24 16:32:01Z

0

$new_array = krsort(array_keys($your_array));

answered Aug 24, 2010 at 16:32

Alex Pliutau

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1 Comment

NullUserException Over a year ago

-1 (1) this does not work (2) you should not pass the result of a function to ksort() (3) ksort() returns a boolean

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