PHP array deduplication method reference (one-dimensional array deduplication, two-dimensional array deduplication)

This article introduces the method of deduplicating PHP arrays, including deduplication of one-dimensional arrays and deduplication of two-dimensional arrays. Friends in need can refer to it.

First, let’s look at how to remove duplicate items from a one-dimensional array.

Use array_unique function, for example:

<?php
  $aa=array("apple","banana","pear","apple","wail","watermalon");
  $bb=array_unique($aa);
  print_r($bb);
  //by bbs.it-home.org
?>

Output result: Array ( [0] => apple [1] => banana [2] => pear [4] => wail [5] => watermalon ) .

Let’s look at how to remove duplicate items from a two-dimensional array.

For two-dimensional arrays, there are two situations to discuss: One is because the value of a certain key name cannot be repeated, so duplicate items are deleted; The other is to remove duplicates because the internal one-dimensional arrays cannot be exactly the same.

Illustrate with specific examples.

1, because the value of a certain key name cannot be repeated, delete the duplicates.

<?php
 function assoc_unique($arr, $key)
  {
    $tmp_arr = array();
    foreach($arr as $k => $v)
   {
      if(in_array($v[$key], $tmp_arr))//搜索$v[$key]是否在$tmp_arr数组中存在，若存在返回true
     {
        unset($arr[$k]);
     }
   else {
       $tmp_arr[] = $v[$key];
     }
   }
 sort($arr); //sort函数对数组进行排序
 return $arr;
 }

 $aa = array(
 array('id' => 123, 'name' => '张三'),
 array('id' => 123, 'name' => '李四'),
 array('id' => 124, 'name' => '王五'),
 array('id' => 125, 'name' => '赵六'),
 array('id' => 126, 'name' => '赵六')
 );
 $key = 'id';
 assoc_unique(&$aa, $key);
 print_r($aa);
 //by bbs.it-home.org
?>

Output result: Array ( [0] => Array ( [id] => 123 [name] => Zhang San) [1] => Array ( [id] => 124 [name] => Wang Wu) [2] => Array ([id] => 125 [name] => Zhao Liu) [3] => Array ( [id] => 126 [name] => Zhao Liu ) )

2. Because the internal one-dimensional arrays cannot be exactly the same, duplicate items are deleted

<?php
 function array_unique_fb($array2D){
      foreach ($array2D as $v){
          $v = join(",",$v); //降维,也可以用implode,将一维数组转换为用逗号连接的字符串
          $temp[] = $v;
      }
      $temp = array_unique($temp);    //去掉重复的字符串,也就是重复的一维数组
     foreach ($temp as $k => $v){
         $temp[$k] = explode(",",$v);   //再将拆开的数组重新组装
     }
     return $temp;
 }

 $aa = array(
 array('id' => 123, 'name' => '张三'),
 array('id' => 123, 'name' => '李四'),
 array('id' => 124, 'name' => '王五'),
 array('id' => 123, 'name' => '李四'),
 array('id' => 126, 'name' => '赵六')
 );
 $bb=array_unique_fb($aa);
 print_r($bb);
 //by bbs.it-home.org
?>

Output result:

Array ( [0] => Array ( [0] => 123 [1] => Zhang San) [1] => Array ( [0] => 123 [1] => Li Si) [2] => Array ( [0] => 124 [1] => Wang Wu) [4] => Array ( [0] => 126 [1] => Zhao Liu ) )