shuffle()

(PHP 4, PHP 5, PHP 7)

打乱数组

说明

本函数打乱（随机排列单元的顺序）一个数组。它使用的是伪随机数产生器，并不适合密码学的场合。

If two members compare as equal, their relative order in the sorted array is undefined.

参数

待操作的数组。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

更新日志

范例

Example #1shuffle()例子

注释

Note:此函数为$array中的元素赋与新的键名。这将删除原有的键名，而不是仅仅将键名重新排序。

参见

• array_rand() 从数组中随机取出一个或多个单元
• 数组排序函数对比

shuffle for associative arrays, preserves key=>value pairs.
(Based on (Vladimir Kornea of typetango.com)'s function) 

*note: as of PHP 5.2.10, array_rand's resulting array of keys is no longer shuffled, so we use array_keys + shuffle.

Shuffle associative and non-associative array while preserving key, value pairs. Also returns the shuffled array instead of shuffling it in place. 

This seems to do reasonably well as a shuffle() that preserves index assocation:

Obviously only works if PHP has closures enabled...

I needed a simple function two shuffle a two dimensional array. Please note the second level arrays must be indexed using integers, for example $myarray[0]["Name"] and not $myarray["One"]["Name"]. Here is the function:

Please note it only works on two dimensional arrays. Here is an example:

Hope you find it useful!

If you want the Power Set (set of all unique subsets) of an array instead of permutations, you can use this simple algorithm: 

There is an function which uses native shuffle() but preserves keys, and their order, so at end, only values are shuffled.

Result example:
Before (original):
Array
(
  [ZERO] => 0
  [ONE] => 1
  [TWO] => 2
  [THREE] => 3
  [FOUR] => 4
  [FIVE] => 5
  [SIX] => 6
  [SEVEN] => 7
  [EIGHT] => 8
  [NINE] => 9
)
After (Array Quake);
Array
(
  [ZERO] => 4
  [ONE] => 2
  [TWO] => 0
  [THREE] => 8
  [FOUR] => 3
  [FIVE] => 6
  [SIX] => 1
  [SEVEN] => 7
  [EIGHT] => 5
  [NINE] => 9
)

Building on examples by m227 and pineappleclock, here is a function that returns all permutations of each set in the power set of an array of strings (instead of a string). Thanks for the great examples! 

Here i wrote a custom shuffle function which preserves the array index and distributes the array element randomly. 

Here is a quick function I wrote that generates a random password and uses shuffle() to easily shuffle the order. 

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