Sort 2dim array by column value [duplicate]

Question

I have a data structure that looks like

Array ( [0] => Array ( [0] => something [1] => 1296986500 ) [1] => Array ( [0] => something else [1] => 1296600100 ) [2] => Array ( [0] => another thing [1] => 1296831265 ) )

I'm trying to sort the array based off of the integer which is a unix timestamp. The following function looks right to me but is not sorting the way I want.

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

NOTE when calling this function within a class the OO syntax is the following

uasort($_data, array($this, 'cmp'));

Brian, if you're going to ask people to help you, at least put yourself in their shoes for 2 seconds and think about whether you actually told them what you want help with or not... — Dan Grossman
– Dan Grossman, Commented Feb 6, 2011 at 3:17
@Dan, Sorry I mean't to sort the array by integer in decreasing order — Brian
– Brian, Commented Feb 8, 2011 at 1:32
What you needed to say was "this code does sort the array by timestamp in ascending order, but I want to sort the array by timestamp in descending order". Instead you leave it where nobody can tell if your sort function works (there could be hidden bugs in code you didn't share), why you say it isn't the way you want, and what it is that you do want. — Dan Grossman
– Dan Grossman, Commented Feb 8, 2011 at 2:41

BoltClock · Accepted Answer · 2011-02-06 03:18:45Z

3

That sorts your timestamps in ascending order; for descending order, flip the second comparison (i.e. change $a[1] < $b[1] to $a[1] > $b[1]):

function cmp($a, $b) { if ($a[1] == $b[1]) { return 0; } return ($a[1] > $b[1]) ? -1 : 1; }

answered Feb 6, 2011 at 3:18

BoltClock

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2 Comments

Felix Kling Over a year ago

Or just return $b[1] - $a[1]; (or vice versa... whatever).

BoltClock Over a year ago

@Felix Kling: Yep, was just trying to match his existing code, along with trying to read his mind.

Chuck Morris · Accepted Answer · 2011-02-06 03:32:22Z

You can setup time stamp as pivot. And use array_multisort().

<?php // Obtain a list of columns foreach ($data as $key => $row) { $time[$key] = $row[1]; //unix timestamp } array_multisort( $time, SORT_ASC, $data); ?>

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