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Revision Autor Zeilennr. Zeile
148 lars 1 
<?php
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namespace Faker\Provider;
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class Biased extends Base
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{
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    /**
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     * Returns a biased integer between $min and $max (both inclusive).
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     * The distribution depends on $function.
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     *
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     * The algorithm creates two doubles, x ∈ [0, 1], y ∈ [0, 1) and checks whether the
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     * return value of $function for x is greater than or equal to y. If this is
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     * the case the number is accepted and x is mapped to the appropriate integer
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     * between $min and $max. Otherwise two new doubles are created until the pair
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     * is accepted.
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     *
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     * @param int      $min      Minimum value of the generated integers.
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     * @param int      $max      Maximum value of the generated integers.
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     * @param callable $function A function mapping x ∈ [0, 1] onto a double ∈ [0, 1]
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     *
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     * @return int An integer between $min and $max.
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     */
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    public function biasedNumberBetween($min = 0, $max = 100, $function = 'sqrt')
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    {
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        do {
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            $x = mt_rand() / mt_getrandmax();
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            $y = mt_rand() / (mt_getrandmax() + 1);
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        } while (call_user_func($function, $x) < $y);
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        return (int) floor($x * ($max - $min + 1) + $min);
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    }
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    /**
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     * 'unbiased' creates an unbiased distribution by giving
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     * each value the same value of one.
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     *
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     * @return int
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     */
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    protected static function unbiased()
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    {
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        return 1;
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    }
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    /**
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     * 'linearLow' favors lower numbers. The probability decreases
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     * in a linear fashion.
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     *
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     * @return int
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     */
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    protected static function linearLow($x)
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    {
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        return 1 - $x;
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    }
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    /**
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     * 'linearHigh' favors higher numbers. The probability increases
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     * in a linear fashion.
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     *
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     * @return int
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     */
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    protected static function linearHigh($x)
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    {
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        return $x;
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    }
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}