29 lines
615 B
PHP
29 lines
615 B
PHP
<?php
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function s_of_n_creator($n) {
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$sample = array();
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$i = 0;
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return function($item) use (&$sample, &$i, $n) {
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$i++;
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if ($i <= $n) {
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// Keep first n items
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$sample[] = $item;
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} else if (rand(0, $i-1) < $n) {
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// Keep item
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$sample[rand(0, $n-1)] = $item;
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}
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return $sample;
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};
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}
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$items = range(0, 9);
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for ($trial = 0; $trial < 100000; $trial++) {
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$s_of_n = s_of_n_creator(3);
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foreach ($items as $item)
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$sample = $s_of_n($item);
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foreach ($sample as $s)
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$bin[$s]++;
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}
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print_r($bin);
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?>
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