array_multisort (PHP 4, PHP 5) array_multisort -- Sort multiple or multi-dimensional arrays Descriptionbool array_multisort ( array ar1 [, mixed arg [, mixed ... [, array ...]]] )
Returns TRUE on success or FALSE on failure.
array_multisort() can be used to sort several
arrays at once, or a multi-dimensional array by one or more
dimensions.
Associative (string) keys will be maintained, but numeric
keys will be re-indexed.
The input arrays are treated as columns of a table to be sorted
by rows - this resembles the functionality of SQL ORDER BY
clause. The first array is the primary one to sort by. The rows
(values) in that array that compare the same are sorted by the
next input array, and so on.
The argument structure of this function is a bit unusual, but
flexible. The first argument has to be an array. Subsequently,
each argument can be either an array or a sorting flag from the
following lists.
Sorting order flags:
Sorting type flags:
SORT_REGULAR - Compare items normally SORT_NUMERIC - Compare items numerically SORT_STRING - Compare items as strings
No two sorting flags of the same type can be specified after each
array. The sorting flags specified after an array argument apply
only to that array - they are reset to default SORT_ASC and
SORT_REGULAR before each new array argument.
Example 1. Sorting multiple arrays
<?php
$ar1 = array("10", 100, 100, "a");
$ar2 = array(1, 3, "2", 1);
array_multisort($ar1, $ar2);
var_dump($ar1);
var_dump($ar2);
?>
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In this example, after sorting, the first array will contain "10",
"a", 100, 100. The second array will contain 1, 1, "2", 3. The
entries in the second array corresponding to the identical
entries in the first array (100 and 100) were sorted as well.
array(4) {
[0]=> string(2) "10"
[1]=> string(1) "a"
[2]=> int(100)
[3]=> int(100)
}
array(4) {
[0]=> int(1)
[1]=> int(1)
[2]=> string(1) "2"
[3]=> int(3)
} |
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Example 2. Sorting multi-dimensional array
<?php
$ar = array(
array("10", 11, 100, 100, "a"),
array( 1, 2, "2", 3, 1)
);
array_multisort($ar[0], SORT_ASC, SORT_STRING,
$ar[1], SORT_NUMERIC, SORT_DESC);
var_dump($ar);
?>
|
In this example, after sorting, the first array will transform to
"10", 100, 100, 11, "a" (it was sorted as strings in ascending
order). The second will contain 1, 3, "2", 2, 1 (sorted as numbers,
in descending order).
array(2) {
[0]=> array(5) {
[0]=> string(2) "10"
[1]=> int(100)
[2]=> int(100)
[3]=> int(11)
[4]=> string(1) "a"
}
[1]=> array(5) {
[0]=> int(1)
[1]=> int(3)
[2]=> string(1) "2"
[3]=> int(2)
[4]=> int(1)
}
} |
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Example 3. Sorting database results
For this example, each element in the data
array represents one row in a table. This type of dataset is typical
of database records.
Example data:
volume | edition
-------+--------
67 | 2
86 | 1
85 | 6
98 | 2
86 | 6
67 | 7 |
The data as an array, called data. This would usually,
for example, be obtained by looping with mysql_fetch_assoc().
<?php
$data[] = array('volume' => 67, 'edition' => 2);
$data[] = array('volume' => 86, 'edition' => 1);
$data[] = array('volume' => 85, 'edition' => 6);
$data[] = array('volume' => 98, 'edition' => 2);
$data[] = array('volume' => 86, 'edition' => 6);
$data[] = array('volume' => 67, 'edition' => 7);
?>
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In this example, we will order by volume descending,
edition ascending.
We have an array of rows, but array_multisort()
requires an array of columns, so we use the below code to obtain the
columns, then perform the sorting.
<?php
// Obtain a list of columns
foreach ($data as $key => $row) {
$volume[$key] = $row['volume'];
$edition[$key] = $row['edition'];
}
// Sort the data with volume descending, edition ascending
// Add $data as the last parameter, to sort by the common key
array_multisort($volume, SORT_DESC, $edition, SORT_ASC, $data);
?>
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The dataset is now sorted, and will look like this:
volume | edition
-------+--------
98 | 2
86 | 1
86 | 6
85 | 6
67 | 2
67 | 7 |
|
Example 4. Case insensitive sorting
Both SORT_STRING and
SORT_REGULAR are case sensitive, strings
starting with a capital letter will come before strings starting
with a lowercase letter.
To perform a case insensitive search, force the sorting order to be
determined by a lowercase copy of the original array.
<?php
$array = array('Alpha', 'atomic', 'Beta', 'bank');
$array_lowercase = array_map('strtolower', $array);
array_multisort($array_lowercase, SORT_ASC, SORT_STRING, $array);
print_r($array);
?>
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The above example will output: Array
(
[0] => Alpha
[1] => atomic
[2] => bank
[3] => Beta
) |
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