php多维数组的去重（针对任意的键值进行去重）--二维数组的唯一--时间复杂度~O(n)

以二维数组为例，来说明针对任意键值的去重，时间复杂度为~O(n)，只用一个foreach循环：

<?php 
$arr = array(
                     "0"=>array(
                            "name"=>"james",
                            "age"=>30,
                              ),
                     "1"=>array(
                            "name"=>"susu",
                            "age"=>26,
                             ),
                     "2"=>array(
                            "name"=>"james",
                            "age"=>30,
                              ),
                     "new"=>array(
                            "name"=>"kube",
                            "age"=>37,
                              ),
                     "list"=>array(
                            "name"=>"kube",
                            "age"=>27,
                              ),
                    );
 /*针对任意键值来进行去重*/
               function getArrayUniqueByKeys($arr)
               {
                   $arr_out =array();
                   foreach($arr as $k => $v)
                   {
                        $key_out = $v["name"]."-".$v["age"]; //提取内部一维数组的key(name age)作为外部数组的键

                        if(array_key_exists($key_out,$arr_out)){
                            continue;
                        }
                        else{
                             $arr_out[$key_out] = $arr[$k]; //以key_out作为外部数组的键
                             $arr_wish[$k] = $arr[$k];  //实现二维数组唯一性
                        }
                   }
                   return $arr_wish;
               }
               $arr_wish = getArrayUniqueByKeys($arr);
               printf("As for the arbitrarily key:<br>");
               print_r($arr_wish);
               echo "<br/>";

?>

输出结果：

As for the arbitrarily key:
Array ( [0] => Array ( [name] => james [age] => 30 ) [1] => Array ( [name] => susu [age] => 26 ) [new] => Array ( [name] => kube [age] => 37 ) [list] => Array ( [name] => kube [age] => 27 ) ) 

开发实例：优惠券去重（以 优惠金额-订单金额字段不能重复去除重复项）

要求：优惠金额和订单金额都一样的优惠券要求只展示一张给用户选择，并且展示最快到期的那张： 

<?php
       $arrCoupon = array(
            "0"=>array(
                "couponCode" => "3033323852301056",
                "usableStartTime" => "1439740800",
                "usableEndTime"=>"1440798100",
                "couponAmount"  =>100,
                "orderAmount"=> 800,
                ),
            "1"=>array(
                "couponCode" => "3033323852301057",
                "usableStartTime" => "1439740800",
                "usableEndTime"=>"1440768100",
                "couponAmount"  =>100,
                "orderAmount"=> 800,
            ),
            "2"=>array(
                "couponCode" => "3033323852301058",
                "usableStartTime" => "1439740800",
                "usableEndTime"=>"1440788100",
                "couponAmount"  =>100,
                "orderAmount"=> 800,
            ),
            "3"=>array(
                "couponCode" => "3033323852301059",
                "usableStartTime" => "1439740800",
                "usableEndTime"=>"1440779100",
                "couponAmount"  =>200,
                "orderAmount"=> 800,
            ),
            "4"=>array(
                "couponCode" => "3033323852301060",
                "usableStartTime" => "1439740800",
                "usableEndTime"=>"1440758100",
                "couponAmount"  =>200,
                "orderAmount"=> 800,
            ),
            "5"=>array(
                "couponCode" => "3033323852301061",
                "usableStartTime" => "1439740800",
                "usableEndTime"=>"1440798100",
                "couponAmount"  =>200,
                "orderAmount"=> 800,
            ),
        );
        //print_r($arrCoupon);
        function getArrayUniqueByKey($arr)
        {
        $arrWish = array();
        $today = time();
        foreach ($arr as $k => $v) {
            if (($v["usableStartTime"] <= $today) && ($today <= $v["usableEndTime"])) { //先确定优惠券的可用日期
                $keyOut = $v["couponAmount"] . "-" . $v["orderAmount"]; 
                //提取内部一维数组的key(couponAmount orderAmount)作为外部数组的键
                if (array_key_exists($keyOut, $arrWish)) {
                    //展现最先到期的优惠券
                    if (intval($arrWish[$keyOut]["usableEndTime"]) > intval($v["usableEndTime"])) {
                        $arrWish[$keyOut] = $v;  //如果原来数组中结束时间大的话，就交换值
                    }
                    continue;
                }
                $arrWish[$keyOut] = $v;  //实现二维数组唯一性
            }
            continue;
        }
        return $arrWish;
        }
        $arrWant = getArrayUniqueByKey($arrCoupon);
        print_r($arrWant);
?>

输出结果：

Array( [100-800] =>Array ( [couponCode] => 3033323852301057 [usableStartTime] => 1439740800[usableEndTime] => 1440768100 [couponAmount] => 100 [orderAmount] =>800 ) [200-800]=> Array ( [couponCode] => 3033323852301060 [usableStartTime] =>1439740800 [usableEndTime] => 1440758100 [couponAmount] => 200 [orderAmount]=> 800 ) )