php 数组去重方法小结

数组中重复项的去除

一维数组的重复项：

使用array_unique函数即可，使用实例如下：

 <?php
   $aa=array("apple","banana","pear","apple","wail","watermalon");
   $bb=array_unique($aa);
   print_r($bb);
?>

结果如下：Array ( [0] => apple [1] => banana [2] => pear [4] => wail [5] => watermalon ) 。

二维数组的重复项：

 对于二维数组咱们分两种情况讨论，一种是因为某一键名的值不能重复，删除重复项；另一种因为内部的一维数组不能完全相同，而删除重复项，下面举例说明：

 ㈠因为某一键名的值不能重复，删除重复项

           

<?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(&#39;id&#39; => 123, &#39;name&#39; => &#39;张三&#39;),
array(&#39;id&#39; => 123, &#39;name&#39; => &#39;李四&#39;),
array(&#39;id&#39; => 124, &#39;name&#39; => &#39;王五&#39;),
array(&#39;id&#39; => 125, &#39;name&#39; => &#39;赵六&#39;),
array(&#39;id&#39; => 126, &#39;name&#39; => &#39;赵六&#39;)
);
$key = &#39;id&#39;;
assoc_unique(&$aa, $key);
print_r($aa);
?>

显示结果为：Array ( [0] => Array ( [id] => 123 [name] => 张三 ) [1] => Array ( [id] => 124 [name] => 王五 ) [2] => Array ( [id] => 125 [name] => 赵六 ) [3] => Array ( [id] => 126 [name] => 赵六 ) )

 ㈡因内部的一维数组不能完全相同，而删除重复项

            

<?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(&#39;id&#39; => 123, &#39;name&#39; => &#39;张三&#39;),
array(&#39;id&#39; => 123, &#39;name&#39; => &#39;李四&#39;),
array(&#39;id&#39; => 124, &#39;name&#39; => &#39;王五&#39;),
array(&#39;id&#39; => 123, &#39;name&#39; => &#39;李四&#39;),
array(&#39;id&#39; => 126, &#39;name&#39; => &#39;赵六&#39;)
);
$bb=array_unique_fb($aa);
print_r($bb)
?>

显示结果：Array ( [0] => Array ( [0] => 123 [1] => 张三 ) [1] => Array ( [0] => 123 [1] => 李四 ) [2] => Array ( [0] => 124 [1] => 王五 ) [4] => Array ( [0] => 126 [1] => 赵六 ) )