php 数组去重

php 数组去重

数组中重复项的去除

2010-07-28 15:29

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('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);
            ?>

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('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)
            ?>

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 ) )