在php中从多维数组中提取重复的值

Question

我有一个这样的数组

 $non_unique_zip
          [0]->[0]91390
               [1]ca
               [2]1
          [1]->[0]91391
               [1]ca
               [2]1
          [2]->[0]91392
               [1]ca
               [2]1
           [3]->[0]91390
                [1]ca
                [2]2
           [4]->[0]91394
                [1]ca
                [2]2

所以基本上数组有元素，其中arra[n][0]是zipcode和数组[n][2]是buyer_id。现在，我只想要有多个买家的邮政编码。所以我唯一想提取的是

[0]->[0]91390
     [1]ca

，因为91390是唯一的邮政编码，其中买方为1和2。我试着

$result = array();
$first = $non_unique_zip[0];
for($i=0; $i<count($non_unique_zip); $i++){
    $result = array_intersect ($first, $non_unique_zip[$i]);
    $first = $result;
}

但是它只是给出了错误未定义的偏移量。

Answer 1

如果您将$records称为您的起始数组，那么这里有一种方法可以使用3行代码获得zip:

//array whose keys are zips, and values are # of occurances
$zips = array_count_values(array_column($records,0));
//filter keeps only zips which occur more than once.
$zips = array_filter($zips,function($n){return $n>1;});
//if you only need the zips, you're done! they are the keys
$zips = array_keys($zips);

现场演示

Answer 2

使用一个数组来跟踪以前已经遇到的邮政编码。然后当你得到那个数组中的zip文件时，你就知道它是重复的。

$zips = array();
$result = array();
foreach ($non_unique_zip as $e) {
    $code = $e[0];
    if (isset($zips[$code])) { // duplicate, so add to $result
        $result[$code] = array($code, $e[1]);
    } else {
        $zips[$code] = true; // first time, add it to $zips
    }
}

Answer 3

像这样使用array_walk:

    <?php
        $non_unique_zip = [
            [91390, "ca"],
            [91391, "ca"],
            [91392, "ca"],
            [91390, "ca"],
            [91394, "ca"],
        ];
        $unique_zip = [];
        $duplicates = [];
        array_walk($non_unique_zip, function($data) use(&$unique_zip, &$duplicates){
            if(!in_array($data, $unique_zip)){
                $unique_zip[] = $data;
            }else{
                $duplicates[] = $data;
            }
        });

        var_dump( $duplicates );
        // PRODUCES::
        array (size=1)
          0 =>
            array (size=2)
              0 => int 91390
              1 => string 'ca' (length=2)

        var_dump( $unique_zip );
        // PRODUCES::
        array (size=4)
          0 => 
            array (size=2)
              0 => int 91390
              1 => string 'ca' (length=2)
          1 => 
            array (size=2)
              0 => int 91391
              1 => string 'ca' (length=2)
          2 => 
            array (size=2)
              0 => int 91392
              1 => string 'ca' (length=2)
          3 => 
            array (size=2)
              0 => int 91394
              1 => string 'ca' (length=2)