Multidimensional array sorting in php [duplicate] - php

Question

This question already has answers here:
How can I sort arrays and data in PHP?
(14 answers)
Closed 6 years ago.
One of my function return this array... Yes I have seen other examples here on SO but non where able to solve my problem.
array (size=4)
0 =>
array (size=2)
'refferrer' => string 'http://google.com/' (length=18)
'number_of_reffers' => string '15' (length=2)
1 =>
array (size=2)
'refferrer' => string 'https://facebook.com/' (length=21)
'number_of_reffers' => string '22' (length=2)
2 =>
array (size=2)
'refferrer' => string 'none' (length=4)
'number_of_reffers' => string '74' (length=2)
3 =>
array (size=2)
'refferrer' => string 'http://findy.com/' (length=17)
'number_of_reffers' => string '6' (length=1)
I will like to know how to sort this array in descending and asscending order using the
'number_of_reffers'...
What I am trying to say is that i want the one with the hishest number_of_reffers to come first, follow by the next and so on.
Is this possible and how can i do this in php.
Thanks for you help.

Answer 1

You need usort
Given your array, you would then do this:
usort( $array, 'sort_by_referrer_count' );
var_dump($array);
// This will sort ascending
function sort_by_referrer_count( $a, $b ) {
// Some defensive coding to ensure keys exist
$a = ( isset( $a['number_of_referrers'] ) ) ? $a['number_of_referrers'] : 0;
$b = ( isset( $b['number_of_referrers'] ) ) ? $b['number_of_referrers'] : 0;
if ($a == $b) {
return 0;
}
return ( $a < $b ) ? -1 : 1;
}
If you want descending, then you could do this (using the same function above):
usort( $array, 'sort_by_referrer_count' );
$array = array_reverse( $array );

Answer 2

In the most simplest sense; you may just want to try this:
<?php
// SORTING ALGORITHM:
// TO SORT IN THE OPPOSITE SENSE...
// (IE. ASCENDING [AS OPPOSED TO THE DEFAULT: DESCENDING]
// CHANGE THE LESS THAN (<) BELOW TO GREATER THAN (>)
function orderByNumRef($arrPrev, $arrNext) {
if ($arrPrev['number_of_reffers'] == $arrNext['number_of_reffers']) {
return 0;
}
return ($arrPrev['number_of_reffers'] < $arrNext['number_of_reffers']) ? -1 : 1;
}
//GIVEN ARRAY - DYNAMIC OR HARD-CODED
$arr = array(
array(
'refferrer' => 'http://google.com/',
'number_of_reffers' =>'15',
),
array(
'refferrer' => 'https://facebook.com/',
'number_of_reffers' =>'74',
),
array(
'refferrer' => 'http://findy.com/',
'number_of_reffers' =>'6',
),
);
//BEFORE SORTING:
var_dump($arr);
uasort($arr, 'orderByNumRef');
//AFTER SORTING:
var_dump($arr);
Hope it helps...

Answer 3

Try this:
<?php
$my_array;
//Sort Acceding
usort($my_array, create_function('$a,$b', 'return (Int)$a["number_of_reffers"]-(Int)$b["number_of_reffers"];'));
//Or sort Descending
usort($my_array, create_function('$a,$b', 'return (Int)$b["number_of_reffers"]-(Int)$a["number_of_reffers"];'));

Answer 4

The easiest way I find to do it is by creating a new array with the number_of_reffers as the key. Then sort the new array with either ksort() or krsort(). This in the end leaves the original array intact. Otherwise creating the original array in the intended format would be better.
<?php
// original array
$array = array(
array('refferrer' => 'http://google.com/', 'number_of_reffers' => '15'),
array('refferrer' => 'https://facebook.com/', 'number_of_reffers' => '22'),
array('refferrer' => 'none', 'number_of_reffers' => '74'),
array('refferrer' => 'http://findy.com/', 'number_of_reffers' => '6')
);
$foo = array(); // new empty array
// loop through $array, assign the number_of_reffers as the key for the refferrer
foreach ($array as $key => $bar) {
$foo[$bar['number_of_reffers']] = $bar['refferrer'];
}
/*
new array will be:
array(
'15' => 'http://google.com/',
'22' => 'https://facebook.com/'
etc .....
)
*/
// use Ksort / Krsort to sort the key asc or desc
ksort($foo); // ascending order
#krsort($foo); // descending order
die('<pre>'.print_r($foo, true).'</pre>'); // pretty printing of sorted array
?>
As a function ....
<?php
Function Referrer_sort($array, $asc = true) {
IF (!is_array($array)) { return 'not an array'; }
$result = array();
foreach ($array as $key => $value) {
$result[$value['number_of_reffers']] = $value['refferrer'];
}
switch ($asc) {
case false: krsort($result); return $result;
default: ksort($result); return $result;
}
}
$foo_asc = Referrer_sort($array);
$foo_desc = Referrer_sort($array, false);
die('<pre>Ascending:<br>'.print_r($foo_asc, true).'<br>Descending:<br>'.print_r($foo_desc, true).'</pre>');
?>
Changing the original array
Modifying the original array by changing the index key with the value of number_of_reffers.
<?php
Function Rebuild_Referrer_sort($array, $asc = true) {
IF (!is_array($array)) { return 'not an array'; }
$result = array();
foreach ($array as $key => $value) {
$result[$value['number_of_reffers']] = array('refferrer' => $value['refferrer'], 'number_of_reffers' => $value['number_of_reffers']);
}
switch ($asc) {
case false: krsort($result); return $result;
default: ksort($result); return $result;
}
}
$foo_asc = Rebuild_Referrer_sort($array);
$foo_desc = Rebuild_Referrer_sort($array, false);
die('<pre>Ascending:<br>'.print_r($foo_asc, true).'<br>Descending:<br>'.print_r($foo_desc, true).'</pre>');
/**
Returns:
Ascending:
Array
(
[6] => Array
(
[refferrer] => http://findy.com/
[number_of_reffers] => 6
)
[15] => Array
(
[refferrer] => http://google.com/
[number_of_reffers] => 15
)
[22] => Array
(
[refferrer] => https://facebook.com/
[number_of_reffers] => 22
)
[74] => Array
(
[refferrer] => none
[number_of_reffers] => 74
)
)
Descending:
Array
(
[74] => Array
(
[refferrer] => none
[number_of_reffers] => 74
)
[22] => Array
(
[refferrer] => https://facebook.com/
[number_of_reffers] => 22
)
[15] => Array
(
[refferrer] => http://google.com/
[number_of_reffers] => 15
)
[6] => Array
(
[refferrer] => http://findy.com/
[number_of_reffers] => 6
)
)
*/
?>