How to sort an array of arrays in php? - php

Question

In php I have a numerical array of associative arrays:
mainArray:
[
array1:['title':'Record a','order':'2'],
array2:['title':'Record b','order':'4'],
array3:['title':'Record c','order':'1'],
array4:['title':'Record d','order':'3']
]
What is the simplest way to sort mainArray by the 'order' value of each associative array?
Thanks

Answer 1

You can use usort function. Since PHP 5.4 you can use closure function:
usort($mainArray, function ($a, $b) {
$a_val = (int) $a['order'];
$b_val = (int) $b['order'];
if($a_val > $b_val) return 1;
if($a_val < $b_val) return -1;
return 0;
});
Or version for PHP < 5.4:
usort($mainArray, 'myCompare');
function myCompare($a, $b) {
$a_val = (int) $a['order'];
$b_val = (int) $b['order'];
if($a_val > $b_val) return 1;
if($a_val < $b_val) return -1;
return 0;
}

Answer 2

The simplest version, using comparison function and usort:
usort($mainArray, function($a, $b) {
return $a['order'] - $b['order'];
});

Answer 3

I found this in the php documentation comments for asort() See also the sort() page, in the comments there are a few good candidates.
function named_records_sort($named_recs, $order_by, $rev=false, $flags=0)
{// Create 1-dimensional named array with just
// sortfield (in stead of record) values
$named_hash = array();
foreach($named_recs as $key=>$fields)
$named_hash["$key"] = $fields[$order_by];
// Order 1-dimensional array,
// maintaining key-value relations
if($reverse) arsort($named_hash,$flags=0) ;
else asort($named_hash, $flags=0);
// Create copy of named records array
// in order of sortarray
$sorted_records = array();
foreach($named_hash as $key=>$val)
$sorted_records["$key"]= $named_recs[$key];
return $sorted_records;} // named_recs_sort()
function show_sorted_records($named_recs, $order_by, $rev=false, $flags=0)
{$sorted_records=named_records_sort($named_recs, $order_by, $rev, $flags);
foreach($sorted_records as $name=>$fields)
{echo "<b>$name</b> ";
foreach($fields as $field=>$val)
echo "$field = $val "; echo "<br>";}
} // show_sorted_records()
$girl_friends=array();
$girl_friends["Anna"]=
array("born"=>'1989-08-22',"cupsize"=>'B-',"IQ"=>105, "daddy"=>'rich');
$girl_friends["Zoe"]
=array("born"=>'1978-03-11',"cupsize"=>'C#',"IQ"=>130, "daddy"=>'poor');
$girl_friends["Lilly"]
=array("born"=>'1985-06-16',"cupsize"=>'DD',"IQ"=>90, "daddy"=>'nasty');
$order_by="cupsize"; echo "And the winners are: <br>";
show_sorted_records($girl_friends, $order_by, true);