问题描述
我想从数组中随机选择一个值,但尽可能保持它的唯一性.
I want to select a random value from a array, but keep it unique as long as possible.
例如,如果我从 4 个元素的数组中选择一个值 4 次,则选择的值应该是随机的,但每次都不同.
For example if I'm selecting a value 4 times from a array of 4 elements, the selected value should be random, but different every time.
如果我从 4 个元素的同一个数组中选择它 10 次,那么显然某些值会重复.
If I'm selecting it 10 times from the same array of 4 elements, then obviously some values will be duplicated.
我现在有这个,但我仍然得到重复的值,即使循环运行了 4 次:
I have this right now, but I still get duplicate values, even if the loop is running 4 times:
$arr = $arr_history = ('abc', 'def', 'xyz', 'qqq');
for($i = 1; $i < 5; $i++){
if(empty($arr_history)) $arr_history = $arr;
$selected = $arr_history[array_rand($arr_history, 1)];
unset($arr_history[$selected]);
// do something with $selected here...
}
推荐答案
您几乎做对了.问题是 unset($arr_history[$selected]);
行.$selected
的值不是一个键,而是一个值,所以 unset 不起作用.
You almost have it right. The problem was the unset($arr_history[$selected]);
line. The value of $selected
isn't a key but in fact a value so the unset wouldn't work.
为了保持它与你在那里所拥有的一样:
To keep it the same as what you have up there:
<?php
$arr = $arr_history = array('abc', 'def', 'xyz', 'qqq');
for ( $i = 1; $i < 10; $i++ )
{
// If the history array is empty, re-populate it.
if ( empty($arr_history) )
$arr_history = $arr;
// Select a random key.
$key = array_rand($arr_history, 1);
// Save the record in $selected.
$selected = $arr_history[$key];
// Remove the key/pair from the array.
unset($arr_history[$key]);
// Echo the selected value.
echo $selected . PHP_EOL;
}
或者一个少几行的例子:
Or an example with a few less lines:
<?php
$arr = $arr_history = array('abc', 'def', 'xyz', 'qqq');
for ( $i = 1; $i < 10; $i++ )
{
// If the history array is empty, re-populate it.
if ( empty($arr_history) )
$arr_history = $arr;
// Randomize the array.
array_rand($arr_history);
// Select the last value from the array.
$selected = array_pop($arr_history);
// Echo the selected value.
echo $selected . PHP_EOL;
}
这篇关于从 PHP 数组中获取随机值,但使其唯一的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!