arsort
(PHP 4, PHP 5)
arsort — Sort an array in reverse order and maintain index association
Description
&$array
[, int $sort_flags = SORT_REGULAR
] )This function sorts an array such that array indices maintain their correlation with the array elements they are associated with.
This is used mainly when sorting associative arrays where the actual element order is significant.
Parameters
-
array -
The input array.
-
sort_flags -
You may modify the behavior of the sort using the optional parameter
sort_flags, for details see sort().
Return Values
Returns TRUE on success or FALSE on failure.
Examples
Example #1 arsort() example
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
?>
The above example will output:
a = orange d = lemon b = banana c = apple
The fruits have been sorted in reverse alphabetical order, and the index associated with each element has been maintained.
See Also
- asort() - Sort an array and maintain index association
- The comparison of array sorting functions
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения, относящиеся к переменным и типам
- Массивы
- array_change_key_case
- array_chunk
- array_column
- array_combine
- array_count_values
- array_diff_assoc
- array_diff_key
- array_diff_uassoc
- array_diff_ukey
- array_diff
- array_fill_keys
- array_fill
- array_filter
- array_flip
- array_intersect_assoc
- array_intersect_key
- array_intersect_uassoc
- array_intersect_ukey
- array_intersect
- array_key_exists
- array_keys
- array_map
- array_merge_recursive
- array_merge
- array_multisort
- array_pad
- array_pop
- array_product
- array_push
- array_rand
- array_reduce
- array_replace_recursive
- array_replace
- array_reverse
- array_search
- array_shift
- array_slice
- array_splice
- array_sum
- array_udiff_assoc
- array_udiff_uassoc
- array_udiff
- array_uintersect_assoc
- array_uintersect_uassoc
- array_uintersect
- array_unique
- array_unshift
- array_values
- array_walk_recursive
- array_walk
- array
- arsort
- asort
- compact
- count
- current
- each
- end
- extract
- in_array
- key_exists
- key
- krsort
- ksort
- list
- natcasesort
- natsort
- next
- pos
- prev
- range
- reset
- rsort
- shuffle
- sizeof
- sort
- uasort
- uksort
- usort
Коментарии
If you need to sort a multi-demension array, for example, an array such as
$TeamInfo[$TeamID]["WinRecord"]
$TeamInfo[$TeamID]["LossRecord"]
$TeamInfo[$TeamID]["TieRecord"]
$TeamInfo[$TeamID]["GoalDiff"]
$TeamInfo[$TeamID]["TeamPoints"]
and you have say, 100 teams here, and want to sort by "TeamPoints":
first, create your multi-dimensional array. Now, create another, single dimension array populated with the scores from the first array, and with indexes of corresponding team_id... ie
$foo[25] = 14
$foo[47] = 42
or whatever.
Now, asort or arsort the second array.
Since the array is now sorted by score or wins/losses or whatever you put in it, the indices are all hoopajooped.
If you just walk through the array, grabbing the index of each entry, (look at the asort example. that for loop does just that) then the index you get will point right back to one of the values of the multi-dimensional array.
Not sure if that's clear, but mail me if it isn't...
-mo
Needed to get the index of the max/highest value in an assoc array.
max() only returned the value, no index, so I did this instead.
<?php
reset($x); // optional.
arsort($x);
$key_of_max = key($x); // returns the index.
?>
I have two servers; one running 5.6 and another that is running 7. Using this function on the two servers gets me different results when all of the values are the same.
<?php
$list = json_decode('{"706":2,"703":2,"702":2,"696":2,"658":2}', true);
print_r($list);
arsort($list);
echo "<br>";
print_r($list);
?>
PHP 5.6 results:
Array ( [706] => 2 [703] => 2 [702] => 2 [696] => 2 [658] => 2 )
Array ( [658] => 2 [696] => 2 [702] => 2 [703] => 2 [706] => 2 )
PHP 7 results:
Array ( [706] => 2 [703] => 2 [702] => 2 [696] => 2 [658] => 2 )
Array ( [706] => 2 [703] => 2 [702] => 2 [696] => 2 [658] => 2 )