Given this array:
$inventory = array(
array("type"=>"fruit", "price"=>3.50),
array("type"=>"milk", "price"=>2.90),
array("type"=>"pork", "price"=>5.43),
);
I would like to sort $inventory's elements by price to get:
$inventory = array(
array("type"=>"pork", "price"=>5.43),
array("type"=>"fruit", "price"=>3.50),
array("type"=>"milk", "price"=>2.90),
);
How can I do this?
You are right; the function you're looking for is array_multisort().
Here's an example taken straight from the manual and adapted to your case:
$price = array();
foreach ($inventory as $key => $row)
{
$price[$key] = $row['price'];
}
array_multisort($price, SORT_DESC, $inventory);
As of PHP 5.5.0, you can use array_column() instead of that foreach:
$price = array_column($inventory, 'price');
array_multisort($price, SORT_DESC, $inventory);
As of PHP 7, this can be done concisely using usort with an anonymous function that uses the spaceship operator to compare elements.
You can do an ascending sort like this:
usort($inventory, function ($item1, $item2) {
return $item1['price'] <=> $item2['price'];
});
Or a descending sort like this:
usort($inventory, function ($item1, $item2) {
return $item2['price'] <=> $item1['price'];
});
To understand how this works, note that usort takes a user-provided comparison function that must behave as follows (from the docs):
The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
And note also that <=>, the spaceship operator,
returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater
which is exactly what usort needs. In fact, almost the entire justification given for adding <=> to the language in https://wiki.php.net/rfc/combined-comparison-operator is that it
makes writing ordering callbacks for use with
usort()easier
PHP 5.3 introduced anonymous functions, but doesn't yet have the spaceship operator. We can still use usort to sort our array, but it's a little more verbose and harder to understand:
usort($inventory, function ($item1, $item2) {
if ($item1['price'] == $item2['price']) return 0;
return $item1['price'] < $item2['price'] ? -1 : 1;
});
Note that although it's fairly common for comparators dealing with integer values to just return the difference of the values, like $item2['price'] - $item1['price'], we can't safely do that in this case. This is because the prices are floating point numbers in the question asker's example, but the comparison function we pass to usort has to return integers for usort to work properly:
Returning non-integer values from the comparison function, such as float, will result in an internal cast to integer of the callback's return value. So values such as 0.99 and 0.1 will both be cast to an integer value of 0, which will compare such values as equal.
This is an important trap to bear in mind when using usort in PHP 5.x! My original version of this answer made this mistake and yet I accrued ten upvotes over thousands of views apparently without anybody noticing the serious bug. The ease with which lackwits like me can screw up comparator functions is precisely the reason that the easier-to-use spaceship operator was added to the language in PHP 7.
uasort. After looking at the docs, though, this answer is still correct in this case. In the OP's example, the array to be sorted has sequential numeric indexes rather than string indexes, so usort is more appropriate. Using uasort on a sequentially-indexed array will result in a sorted array which is not ordered by its numeric indexes, such that the first element seen in a foreach loop is not $your_array[0], which is unlikely to be desirable behaviour.
While others have correctly suggested the use of array_multisort(), for some reason no answer seems to acknowledge the existence of array_column(), which can greatly simplify the solution. So my suggestion would be:
array_multisort(array_column($inventory, 'price'), SORT_DESC, $inventory);
If you want Case Insensitive Sort on strings, you can use SORT_NATURAL|SORT_FLAG_CASE
array_multisort(array_column($inventory, 'key_name'), SORT_DESC, SORT_NATURAL|SORT_FLAG_CASE, $inventory);
Since your array elements are arrays themselves with string keys, your best bet is to define a custom comparison function. It's pretty quick and easy to do. Try this:
function invenDescSort($item1,$item2)
{
if ($item1['price'] == $item2['price']) return 0;
return ($item1['price'] < $item2['price']) ? 1 : -1;
}
usort($inventory,'invenDescSort');
print_r($inventory);
Produces the following:
Array
(
[0] => Array
(
[type] => pork
[price] => 5.43
)
[1] => Array
(
[type] => fruit
[price] => 3.5
)
[2] => Array
(
[type] => milk
[price] => 2.9
)
)
uasort( $inventory, function ($a, $b) { if ( $a==$b ) return 0; else return ($a > $b) ? -1 : 1; });usort seems more appropriate than uasort for sorting an array with sequential numeric keys. Ending up with an array where the first element is at index 1 and the second element is at index 0 is weird behavior and a sure trap for people who aren't familiar with the details of PHP's arrays; usort gives you the output you'd intuitively expect.I ended on this:
function sort_array_of_array(&$array, $subfield)
{
$sortarray = array();
foreach ($array as $key => $row)
{
$sortarray[$key] = $row[$subfield];
}
array_multisort($sortarray, SORT_ASC, $array);
}
Just call the function, passing the array and the name of the field of the second level array. Like:
sort_array_of_array($inventory, 'price');
$key in the temporary $sortarray. This answer can be reduced to one line without the custom function declarationa and the explicit direction constant usage. array_multisort(array_column($array, $subfield), $array);You can use usort with an anonymous function, e.g.,
usort($inventory, function ($a, $b) { return strnatcmp($a['price'], $b['price']); });
strnatcmp, meant for comparing strings, seems to work fine here. Apparently the "natural order" it implements includes sorting numerical strings numerically rather than lexically.From Sort an array of associative arrays by value of given key in PHP:
By using usort, we can sort an array in ascending and descending order. We just need to create a function and pass it as parameter in usort. As per below example used greater than for ascending order if we passed less than condition then it's sort in descending order.
Example:
$array = array(
array('price' => '1000.50', 'product' => 'test1'),
array('price' => '8800.50', 'product' => 'test2'),
array('price' => '200.0' , 'product' => 'test3')
);
function cmp($a, $b) {
return $a['price'] > $b['price'];
}
usort($array, "cmp");
print_r($array);
Output:
Array
(
[0] => Array
(
[price] => 200.0
[product] => test3
)
[1] => Array
(
[price] => 1000.50
[product] => test1
)
[2] => Array
(
[price] => 8800.50
[product] => test2
)
)
cmp function here is wrong. It's supposed to return "an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second" but instead returns true or false. It seems, remarkably, to nonetheless work - perhaps because the current implementation of usort and friends treats the "less than" and "equal to" cases identically - but don't count on it carrying on working in future PHP versions. If they try to make sorts be stable (i.e. not move around equal elements unnecessarily), this will break.usort would be more appropriate than uasort here, since uasort preserves the association between keys and values which is confusing and unexpected when deaing with a sequential numerical array. For instance, the indexes of $array above after calling uasort are 2, 0, and 1, in that order. Unless you for some reason want that, you'll probably be more comfortable using usort, which reindexes the array as well as reordering it.
$inventory =
array(array("type"=>"fruit", "price"=>3.50),
array("type"=>"milk", "price"=>2.90),
array("type"=>"pork", "price"=>5.43),
);
function pricesort($a, $b) {
$a = $a['price'];
$b = $b['price'];
if ($a == $b)
return 0;
return ($a > $b) ? -1 : 1;
}
usort($inventory, "pricesort");
// uksort($inventory, "pricesort");
print("first: ".$inventory[0]['type']."\n\n");
// for usort(): prints milk (item with lowest price)
// for uksort(): prints fruit (item with key 0 in the original $inventory)
// foreach prints the same for usort and uksort.
foreach($inventory as $i){
print($i['type'].": ".$i['price']."\n");
}
outputs:
first: pork
pork: 5.43
fruit: 3.5
milk: 2.9
/**
* Sorts an associative array by a specific key and direction.
*
* @param array $array The associative array to sort.
* @param string $key The key to sort by.
* @param string $direction The sort direction ("ASC" for ascending, "DESC" for descending).
* @return array The sorted associative array.
*/
function sortAssociativeArrayByKey($array, $key, $direction) {
usort($array, function ($a, $b) use ($key, $direction) {
$comparison = $a[$key] <=> $b[$key];
return ($direction === 'DESC') ? -$comparison : $comparison;
});
return $array;
}
As of PHP 7.4, you can use the arrow function:
usort(
$inventory,
fn(array $a, array $b): int => $b['price'] <=> $a['price']
);
Code (demo):
$inventory = [
['type' => 'fruit', 'price' => 3.50],
['type' => 'milk', 'price' => 2.90],
['type' => 'pork', 'price' => 5.43],
];
usort(
$inventory,
fn(array $a, array $b): int => $b['price'] <=> $a['price']
);
print_r($inventory);
(Condensed) output:
Array
(
[0] => Array ([type] => pork, [price] => 5.43)
[1] => Array ([type] => fruit, [price] => 3.5)
[2] => Array ([type] => milk, [price] => 2.9)
)
This was tested on 100,000 records:
Time in seconds (calculated by function microtime). Only for unique values on sorting key positions.
Solution of function of @Josh Davis:
Spent time: 1.58
My solution:
Spent time: 0.094
Solution:
function SortByKeyValue($data, $sortKey, $sort_flags=SORT_ASC)
{
if (empty($data) or empty($sortKey))
return $data;
$ordered = array();
foreach ($data as $key => $value)
$ordered[$value[$sortKey]] = $value;
ksort($ordered, $sort_flags);
return array_values($ordered); *// array_values() added for identical result with multisort*
}
array_column() can do what the foreach() is doing. If there are performance improvements by making key comparisons, it needs to be acknowledged that this answer doubles the memory consumption by populating the new array and as Chris Baker noted, if duplicate values are encountered in the identifying column, then whole rows will be lost. Also, if assigning keys that PHP will truncate (using a float type value as the key) then there may be side effects like lost data.I use uasort like this:
<?php
$users = [
[
'username' => 'joe',
'age' => 11
],
[
'username' => 'rakoto',
'age' => 21
],
[
'username' => 'rabe',
'age' => 17
],
[
'username' => 'fy',
'age' => 19
],
];
uasort($users, function ($item, $compare) {
return $item['username'] >= $compare['username'];
});
var_dump($users);
Try this:
$prices = array_column($inventory, 'price');
array_multisort($prices, SORT_DESC, $inventory);
print_r($inventory);
This function is reusable:
function usortarr(&$array, $key, $callback = 'strnatcasecmp') {
uasort($array, function($a, $b) use($key, $callback) {
return call_user_func($callback, $a[$key], $b[$key]);
});
}
It works well on string values by default, but you'll have to sub the callback for a number comparison function if all your values are numbers.
usortarr but then call uasort instead of usort; perhaps a bit confusing. The latter is - in the case of a sequential array with numerical indexes, like the one exhibited in the question - probably what you actually want.Many people are searching for a way to do this with Laravel and are ending up here. Also, some Laravel questions are getting closed due to duplicates to this question.
Hence, I shared an easy way to perform it with the Laravel collect() method.
$inventory = collect($inventory)->sortBy('price')->toArray();
For Descending order
$inventory = collect($inventory)->sortBy('price')->reverse()->toArray();
Or,
$inventory = collect($inventory)->('price')->reverse()->toArray();
Here is a method that I found long ago and cleaned up a bit. This works great, and can be quickly changed to accept objects as well.
/**
* A method for sorting arrays by a certain key:value.
* SortByKey is the key you wish to sort by
* Direction can be ASC or DESC.
*
* @param $array
* @param $sortByKey
* @param $sortDirection
* @return array
*/
private function sortArray($array, $sortByKey, $sortDirection) {
$sortArray = array();
$tempArray = array();
foreach ( $array as $key => $value ) {
$tempArray[] = strtolower( $value[ $sortByKey ] );
}
if($sortDirection=='ASC'){ asort($tempArray ); }
else{ arsort($tempArray ); }
foreach ( $tempArray as $key => $temp ){
$sortArray[] = $array[ $key ];
}
return $sortArray;
}
to change the method to sort objects simply change the following line:
$tempArray[] = strtolower( $value[ $sortByKey ] );
to
$tempArray[] = strtolower( $value->$sortByKey );
To run the method simply do
sortArray($inventory,'price','ASC');
array_multisort) or mine (with usort) and seems to offer no advantages over them in exchange.
//Just in one line custom function
function cmp($a, $b)
{
return (float) $a['price'] < (float)$b['price'];
}
@uasort($inventory, "cmp");
print_r($inventory);
//result
Array
(
[2] => Array
(
[type] => pork
[price] => 5.43
)
[0] => Array
(
[type] => fruit
[price] => 3.5
)
[1] => Array
(
[type] => milk
[price] => 2.9
)
)
Complete Dynamic Function
I jumped here for associative array sorting and found this amazing function on sort. This function is very dynamic and sort in ascending and descending order with a specified key.
A simple function to sort an array by a specific key.
It maintains the index association.
<?php
function array_sort($array, $on, $order=SORT_ASC)
{
$new_array = array();
$sortable_array = array();
if (count($array) > 0) {
foreach ($array as $k => $v) {
if (is_array($v)) {
foreach ($v as $k2 => $v2) {
if ($k2 == $on) {
$sortable_array[$k] = $v2;
}
}
} else {
$sortable_array[$k] = $v;
}
}
switch ($order) {
case SORT_ASC:
asort($sortable_array);
break;
case SORT_DESC:
arsort($sortable_array);
break;
}
foreach ($sortable_array as $k => $v) {
$new_array[$k] = $array[$k];
}
}
return $new_array;
}
$people = array(
12345 => array(
'id' => 12345,
'first_name' => 'Joe',
'surname' => 'Bloggs',
'age' => 23,
'sex' => 'm'
),
12346 => array(
'id' => 12346,
'first_name' => 'Adam',
'surname' => 'Smith',
'age' => 18,
'sex' => 'm'
),
12347 => array(
'id' => 12347,
'first_name' => 'Amy',
'surname' => 'Jones',
'age' => 21,
'sex' => 'f'
)
);
print_r(array_sort($people, 'age', SORT_DESC)); // Sort by oldest first
print_r(array_sort($people, 'surname', SORT_ASC)); // Sort by surname
if (count($array) > 0) { is unneeded before the foreach(). Is this script over-engineered? I'm not sure I'd use something like this versus a native array_multisort() or usort() call.If you need to sort an array of strings with different cases, this will change the sorting array values to lowercase.
$data = [
[
'name' => 'jack',
'eyeColor' => 'green'
],
[
'name' => 'Amy',
'eyeColor' => 'brown'
],
[
'name' => 'Cody',
'eyeColor' => 'blue'
]
];
function toLowerCase($a) { return strtolower($a); }
$sortArray = array_map("toLowerCase",array_column($data, 'name'));
array_multisort($sortArray, SORT_ASC, $data);
$arr1 = array(
array('id'=>1,'name'=>'aA','cat'=>'cc'),
array('id'=>2,'name'=>'aa','cat'=>'dd'),
array('id'=>3,'name'=>'bb','cat'=>'cc'),
array('id'=>4,'name'=>'bb','cat'=>'dd')
);
$result1 = array_msort($arr1, array('name'=>SORT_DESC);
$result2 = array_msort($arr1, array('cat'=>SORT_ASC);
$result3 = array_msort($arr1, array('name'=>SORT_DESC, 'cat'=>SORT_ASC));
function array_msort($array, $cols)
{
$colarr = array();
foreach ($cols as $col => $order) {
$colarr[$col] = array();
foreach ($array as $k => $row) { $colarr[$col]['_'.$k] = strtolower($row[$col]); }
}
$eval = 'array_multisort(';
foreach ($cols as $col => $order) {
$eval .= '$colarr[\''.$col.'\'],'.$order.',';
}
$eval = substr($eval,0,-1).');';
eval($eval);
$ret = array();
foreach ($colarr as $col => $arr) {
foreach ($arr as $k => $v) {
$k = substr($k,1);
if (!isset($ret[$k])) $ret[$k] = $array[$k];
$ret[$k][$col] = $array[$k][$col];
}
}
return $ret;
}
This function works 100% on all major versions of PHP and it is tested with PHP5, PHP7, PHP8.
function sort_my_array($array, $order_by, $order)
{
switch ($order) {
case "asc":
usort($array, function ($first, $second) use ($order_by) {
if (version_compare(PHP_VERSION, '7.0.0') >= 0) {
return $first[$order_by] <=> $second[$order_by];
} else {
$array_cmp = strcmp($first[$order_by], $second[$order_by]);
return $array_cmp ;
}
});
break;
case "desc":
usort($certificates, function ($first, $second) use ($order_by) {
if (version_compare(PHP_VERSION, '7.0.0') >= 0) {
return $first[$order_by] <=> $second[$order_by];
} else {
$array_cmp = strcmp($first[$order_by], $second[$order_by]);
return -$array_cmp ;
}
});
break;
default:
break;
}
return $array;
}
$order === 'desc', then multiply the returned value by -1. default doesn't need a break. An empty default is pointless. The version comparison will not change during script execution, so it makes no sense to check it on each iteration.try this:
asort($array_to_sort, SORT_NUMERIC);
for reference see this: http://php.net/manual/en/function.asort.php
see various sort flags here: http://www.php.net/manual/en/function.sort.php
pricecolumn comes first andtypecomes second? This way, you can just callrsort(). 3v4l.org/2meqs