book_admin/application/common/helper/ArrayHelper.php

<?php
/**
 * Created by PhpStorm.
 * User: Bear
 * Date: 2019/1/12
 * Time: 下午5:06
 */

namespace app\common\helper;


class ArrayHelper
{
    /**
     * 按照数组权重获取索引
     * @param $proportion
     * @return mixed
     */
    public static function getRateFromArray($proportion)
    {
        $weight_total = 10000;
        $total = array_sum($proportion);
        if(!$total){
            return false;
        }
        $rat = $weight_total / $total;
        $ids = array_keys($proportion);
        $values = array_values($proportion);
        array_multisort($values, $ids);
        foreach ($values as $index => $weight) {
            if ($index == 0) {
                $values[$index] *= $rat;
            } else {
                $values[$index] = $values[$index] * $rat + $values[$index - 1];
            }
            $id = $ids[$index];
        }
        $value = rand(0, $weight_total);
        foreach ($values as $index => $weight) {
            if ($value < $weight && $weight != 0) {
                $id = $ids[$index];
                break;
            }
        }

        return $id;
    }

    /**
     * 从数组中制取元素
     * @param      $array
     * @param      $keys
     * @param null $callback_key
     * @return array
     */
    public static function extractFromArray($array, $keys, $callback_key = NULL)
    {
        $return = [];
        foreach ($keys as $key) {
            if (array_key_exists($key, $array)) {
                if ($callback_key instanceof \Closure) {
                    $newKey = $callback_key($key);
                } else {
                    $newKey = $key;
                }
                $return[$newKey] = $array[$key];
            }
        }

        return $return;
    }

    /**
     * 数组key替换为驼峰命令
     * @param $array
     * @return array
     */
    public static function replaceKeyWithCamel($array)
    {
        $result = [];
        foreach ($array as $index => $item) {
            $newKey = StringHelper::stringToCamel($index);
            $result[$newKey] = $item;
        }

        return $result;
    }

    /**
     * @param        $array
     * @param        $key
     * @param string $default
     * @return string
     */
    public static function arrayGet($array, $key, $default = '')
    {
        if (!is_array($array)) {
            $array = [];
        }
        if (array_key_exists($key, $array)) {
            return $array[$key];
        }

        return $default;
    }
}