Php 从Json数组中删除重复项的算法

我有以下JSON数据：

[{"make":"Cadillac","model":"Escalade","year":"2006"},{"make":"Cadillac","model":"Escalade","year":"2005"},{"make":"Cadillac","model":"Escalade","year":"2004"},{"make":"Cadillac","model":"Escalade","year":"2003"},{"make":"Cadillac","model":"Escalade","year":"2002"},{"make":"Cadillac","model":"Escalade ESV","year":"2006"},{"make":"Cadillac","model":"Escalade ESV","year":"2005"},{"make":"Cadillac","model":"Escalade ESV","year":"2004"},{"make":"Cadillac","model":"Escalade ESV","year":"2003"},{"make":"Cadillac","model":"Escalade EXT","year":"2006"},{"make":"Cadillac","model":"Escalade EXT","year":"2005"},{"make":"Cadillac","model":"Escalade EXT","year":"2004"},{"make":"Cadillac","model":"Escalade EXT","year":"2003"},{"make":"Cadillac","model":"Escalade EXT","year":"2002"},{"make":"Chevrolet","model":"Astro","year":"2005"},{"make":"Chevrolet","model":"Astro","year":"2004"},{"make":"Chevrolet","model":"Astro","year":"2003"},{"make":"Chevrolet","model":"Avalanche 1500","year":"2006"},{"make":"Chevrolet","model":"Avalanche 1500","year":"2005"}]

如何对数据格式进行排序

Cadillac    Escalade    07-13
Cadillac    Escalade ESV    07-13
Cadillac    Escalade EXT    07-13
Cadillac    XTS 2013
Chevrolet   Avalanche   07-13
Chevrolet   Express 1500    09-14

---

我对PHP还是一个新手，所以我很难弄明白如何实现这一点，如何删除重复项，以及如何通过串联增加年份

---

谢谢，

您必须使用循环解析它。其简单版本如下所示：

$cars = json_decode($cars_json);
$carList = array();
foreach($cars as $car){
    if(!isset($carList[$car->make . $car->model])){
        $carList[$car->make . $car->model] = array(
            'firstYear' => $car->year,
            'lastYear' => $car->year,
            'make'=>$car->make,
            'model' => $car->model,
    }
    else{
        if($car->year < $carList[$car->make . $car->model]['firstYear'])
            $carList[$car->make . $car->model]['firstYear'] = $car->year;
        else if($car->year > $carList[$car->make . $car->model]['lastYear'])
            $carList[$car->make . $car->model]['lastYear'] = $car->year;
    }
}
//Parsing complete, now output

foreach($carList as $car){
  echo $car['make'] . " ";
  echo $car['model'] . " ";
  echo substr($car['firstYear'],-2) . "-" . substr($car['lastYear'], -2);
}

$cars=json\u decode（$cars\u json）；
$carList=array（）；
foreach（$cars作为$car）{
如果（！isset（$carList[$car->make.$car->model]））{
$carList[$car->make.$car->model]=数组(
“第一年”=>$car->year，
“去年”=>$car->year，
'make'=>$car->make，
'model'=>$car->model，
}
否则{
如果（$car->year<$carList[$car->make.$car->model]['firstYear']）
$carList[$car->make.$car->model]['firstYear']=$car->year；
否则如果（$car->year>$carList[$car->make.$car->model]['lastYear']）
$carList[$car->make.$car->model]['lastYear']=$car->year；
}
}
//解析完成，现在输出
foreach（$carList作为$car）{
echo$car['make']；
echo$car['model']。“”；
echo substr（$car['firstYear'，-2）。“-”.substr（$car['lastYear'，-2）；
}

产出：

Cadillac    Escalade    2002-2006
Cadillac    Escalade ESV    2003-2006
Cadillac    Escalade EXT    2002-2006
Chevrolet   Astro   2003-2005
Chevrolet   Avalanche 1500  2005-2006

$organized

是在第一个

foreach

中创建的多维数组，如下所示：

Array
(
    [Cadillac] => Array
        (
            [Escalade] => Array
                (
                    [0] => 2006
                    [1] => 2005
                    [2] => 2004
                    [3] => 2003
                    [4] => 2002
                )

            [Escalade ESV] => Array
                (
                    [0] => 2006
                    [1] => 2005
                    [2] => 2004
                    [3] => 2003
                )

            [Escalade EXT] => Array
                (
                    [0] => 2006
                    [1] => 2005
                    [2] => 2004
                    [3] => 2003
                    [4] => 2002
                )

        )

    [Chevrolet] => Array
        (
            [Astro] => Array
                (
                    [0] => 2005
                    [1] => 2004
                    [2] => 2003
                )

            [Avalanche 1500] => Array
                (
                    [0] => 2006
                    [1] => 2005
                )

        )

)

---

什么是

07-13

？它不会出现在你的json数据中，通过串联添加年份。这很优雅，我已经尝试了2天，你能用if语句而不是三元运算来重构吗？也许还可以解释两个foreach循环和排序发生了什么？一些额外的注释，这样我就可以真正掌握l这背后的逻辑。做得好，尽管这正是我想要完成的。@hayonj，我补充了一点细节。我不知道我是否理解“如果（计数（$years））`我会在上面使用for循环，你能解释一下它的作用吗？正如你从我添加到答案中的数组转储中看到的，$years成为JSON数据中所有可用年份的数组。我使用

count（$years）做什么

正在检查是否有更多的值来创建年份范围。

array\u shift

从数组中删除第一项。如果count返回任何内容，我知道我需要创建年份范围。重构前的第一段代码是：

$sorted=array\u map（函数（$arr）{return array\u map（函数（$a）{sort（$a）；return$a；}，$arr）；}，$organized）；

您能解释一下数组映射和匿名函数的情况吗？谢谢。

Array
(
    [Cadillac] => Array
        (
            [Escalade] => Array
                (
                    [0] => 2006
                    [1] => 2005
                    [2] => 2004
                    [3] => 2003
                    [4] => 2002
                )

            [Escalade ESV] => Array
                (
                    [0] => 2006
                    [1] => 2005
                    [2] => 2004
                    [3] => 2003
                )

            [Escalade EXT] => Array
                (
                    [0] => 2006
                    [1] => 2005
                    [2] => 2004
                    [3] => 2003
                    [4] => 2002
                )

        )

    [Chevrolet] => Array
        (
            [Astro] => Array
                (
                    [0] => 2005
                    [1] => 2004
                    [2] => 2003
                )

            [Avalanche 1500] => Array
                (
                    [0] => 2006
                    [1] => 2005
                )

        )

)