PHP切割整数工具类似微信红包金额分配的思路详解

时间:2021-05-26

Composer地址:https://packagist.org/packages/werbenhu/php-number-slicing

GitHub地址:https://github.com/werbenhu/php-number-slicing

主要代码:NumberSlicing.php

思路:将数字按精度放大倍数,比如切割数字1,切割的份数是10,精度是0.01,则将1放大100 X 10倍,然后再来对加了1000倍权重后的值进行切割。切割完成之后,再将权重去除,保证总值是1。

<?phpnamespace Werben\Tools;use Exception;class NumberSlicing { /** * 精确小数点,舍弃最后一位之后的数据(非四舍五入) * floor with precision * @param $number 要精确的数 * @param $precision 精度,比如保留到0.01,则该值为2 * @return float|int */ public static function floorWithPrecision($number, $precision) { $power = pow(10, $precision); $ret = floor($number * $power) * 1.0 / $power ; return $ret; } /** * 精确小数点,按四舍五入保留最后一位 * round with precision * @param $number 要精确的数 * @param $precision 精度,比如保留到0.01,则该值为2 * @return float|int */ public static function roundWithPrecision($number, $precision) { $power = pow(10, $precision); $ret = round($number * $power) * 1.0 / $power ; return $ret; } /** * 将数把权重放大,比如1,要按精度0.0001分配,则先将1乘以10000然后再来分配 * random the sum weights 加上权重之后,整个要切割的数的权重总值 * @param $weight_items 用来保留,随机分配的权重值 * @param $count 要切割的份数 * @param int $each_weight 加上权重之后,每一份平均的权重值 * @param int $min_weight 加上权重之后,最小额度的值 * @return float|int */ public static function weightSlicing(&$weight_items, $count, $each_weight = 10, $min_weight = 3) { $already_count = count($weight_items); $cur_random_full_total = ($already_count + 1) * $each_weight; $already_random_real_total = 0; foreach ($weight_items as $value) { $already_random_real_total += $value; } $cur_random_rest = $cur_random_full_total - $already_random_real_total; if ($already_count == $count - 1) { $cur_random_rate = $cur_random_rest; } else { $cur_random_rate_max = $cur_random_rest + $each_weight - $min_weight * 2; $cur_random_rate = $min_weight + mt_rand(0, $cur_random_rate_max); } $weight_items[] = $cur_random_rate; return $cur_random_rate; } /** * slicing the number * @param int $number * @param int $size * @param float $precision * @param float $min * @return array * @throws Exception */ public static function numberSlicing($number, $size, $precision = 0.01, $min = 0.01) { if ($number * 1.0 / $size <= $min) { throw new Exception('min number is bigger than the average value!'); } if ($precision > 1) { throw new Exception('precision can\'t bigger than 1!'); } if ($min < $precision) { throw new Exception('precision can\'t bigger than min!'); } $weight_items = []; $items = []; //不加权重情况下,每一份的平均值 $each_weight = intval($number / $size); if ($precision < 1) { //如果精度是小数 if ($each_weight > 1) { //如果平均值大于1,则最小额度则直接用min就可以了 //每一份的平均值乘以权重的值,比如精度为0.01,则每一份的平均值要乘以权重(100) $each_weight = intval((1 / $precision) * $number / $size); //最小数值也要乘以权重 $min_weight = intval(1 / $precision) * $min; } else { //如果平均值小于1,需要将平均值也乘以权重 $each_weight = intval(1 / $precision); $min_weight = $each_weight * $size * $min / $number; } $precision_num = log10(1 / $precision); } else { //如果精度是整数(1) $min_weight = $min; $precision_num = 0; } $sum_item_number = 0.0; $sum_weight = 0.0; //先将整个数,随机按最小额度分配 for ($i = 0; $i < $size; $i++) { $cur_weight = self::weightSlicing($weight_items, $size, $each_weight, $min_weight); //将权重去除,换算回原先的比例 $rate = ($number * $cur_weight * 1.00) / ($size * $each_weight); $rate = self::floorWithPrecision($rate, $precision_num); $sum_item_number += $rate; $sum_weight += $cur_weight; $items[] = $rate; } //由于误差,随机分配后,还会遗留一些数没有完全分配完,则将剩下的数随机分配 if ($precision_num != 0) { //如果是切割成小数 $rest = $number - $sum_item_number; while ($rest - 0.00 > PHP_FLOAT_MIN) { if ($rest / $min >= 1.0) { //剩余的数大于min最小额度,则将每份最小额度随机分配 $random_index = mt_rand(0, $size - 1); $items[$random_index] = self::roundWithPrecision($items[$random_index] + $min, $precision_num); $sum_item_number = self::roundWithPrecision($sum_item_number + $min, $precision_num); $rest = self::roundWithPrecision($number - $sum_item_number, $precision_num); } else { //剩余的数小于min最小额度,则将这最后的未分配的数随机分配 $random_index = mt_rand(0, $size - 1); $items[$random_index] = self::roundWithPrecision($items[$random_index] + $number - $sum_item_number, $precision_num); $sum_item_number = $number; $rest = $number - $sum_item_number; } } } else { //如果是切割成整数 $rest = $number - $sum_item_number; while ($rest > 0) { if ($rest / $min >= 1) { $random_index = mt_rand(0, $size - 1); $items[$random_index] += $min; $sum_item_number += $min; $rest = $number - $sum_item_number; } else { $random_index = mt_rand(0, $size - 1); $items[$random_index] += $rest; $sum_item_number += $rest; $rest = $number - $sum_item_number; } } } return $items; }}

  测试代码:

use Werben\Tools\NumberSlicing; function testIntSlicing2IntOne() { $precision = 1; //精确度 eg: 1, 0.1, 0.01, 0.01 $size = 10; //切割的份数,the size of the number to slicing $min = 3; //最小额度,最小额度必须大于最小精度,min amount eg: 3, 0.23, 0.05, 0.008 $number = 100; //要切割的数字,the number $items = NumberSlicing::numberSlicing($number, $size, $precision, $min); $sum = 0.0; $ret_min = $number; foreach ($items as $value) { $sum += $value; if ($ret_min > $value) { $ret_min = $value; } } $count = count($items); echo "count: $count, sum: $sum, ret_min: $ret_min\n"; echo "items : ". json_encode($items) ."\n";}function testIntSlicing2IntTwo() { $precision = 1; //精确度 eg: 1, 0.1, 0.01, 0.01 $size = 30; //切割的份数,the size of the number to slicing $min = 18666; //最小额度,最小额度必须大于最小精度,min amount eg: 3, 0.23, 0.05, 0.008 $number = 800000; //要切割的数字,the number $items = NumberSlicing::numberSlicing($number, $size, $precision, $min); $sum = 0.0; $ret_min = $number; foreach ($items as $value) { $sum += $value; if ($ret_min > $value) { $ret_min = $value; } } $count = count($items); echo "count: $count, sum: $sum, ret_min: $ret_min\n"; echo "items : ". json_encode($items) ."\n";}function testIntSlicing2FloatOne() { $precision = 0.01; //精确度 eg: 1, 0.1, 0.01, 0.01 $size = 1000; //切割的份数,the size of the number to slicing $min = 0.05; //最小额度,最小额度必须大于最小精度,min amount eg: 3, 0.23, 0.05, 0.008 $number = 100; //要切割的数字,the number $items = NumberSlicing::numberSlicing($number, $size, $precision, $min); $sum = 0.0; $ret_min = $number; foreach ($items as $key => $value) { $sum += $value; if ($ret_min > $value) { $ret_min = $value; } } $count = count($items); echo "count: $count, sum: $sum, ret_min: $ret_min\n"; echo "items: ". json_encode($items) ."\n";}function testIntSlicing2FloatTwo() { $precision = 0.00001; //精确度 eg: 1, 0.1, 0.01, 0.01 $size = 1000; //切割的份数,the size of the number to slicing $min = 0.00005; //最小额度,最小额度必须大于最小精度,min amount eg: 3, 0.23, 0.05, 0.008 $number = 5; //要切割的数字,the number $items = NumberSlicing::numberSlicing($number, $size, $precision, $min); $sum = 0.0; $ret_min = $number; foreach ($items as $key => $value) { $sum += $value; if ($ret_min > $value) { $ret_min = $value; } } $count = count($items); echo "count: $count, sum: $sum, ret_min: $ret_min\n"; echo "items: ". json_encode($items) ."\n";}

总结

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