从数组中删除重复项

Question

我使用下面的代码行循环遍历数据库中的表：

$items_thread = $connection -> fetch_all($sql);

如果我打印出数组：

print_r($items_thread);

我会得到这个：

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => [email protected]
        )

    [1] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => [email protected]
        )

    [2] => Array
        (
            [RecipientID] => 1
            [RecipientScreenname] => Lau T
            [RecipientFirstname] => TK
            [RecipientEmail] => [email protected]
        )

)

但我想删除数组中的重复项，所以我使用 array_unique

print_r(array_unique($items_thread));

我得到下面奇怪的结果，这并不完全是我想要的：

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => [email protected]
        )

)

理想情况下，我认为它应该返回这个：

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => [email protected]
        )

    [1] => Array
        (
            [RecipientID] => 1
            [RecipientScreenname] => Lau T
            [RecipientFirstname] => TK
            [RecipientEmail] => [email protected]
        )

)

我该怎么做才能让它正确？我是否使用了错误的 PHP 语法/默认函数？

Answer 1

array_unique 函数将为您完成此操作。您只需要添加 SORT_REGULAR 标志：

$items_thread = array_unique($items_thread, SORT_REGULAR);

但是，如 bren 建议，如果可能的话，您应该在 SQL 中执行此操作。

Answer 2

过滤掉 SQL 查询中的重复项会更好。添加一个获取唯一收件人 ID 的约束

Answer 3

要删除重复值，我们可以使用 array_unique() 函数。它的功能是接受一个数组并返回另一个不重复值的数组。

array_unique() 的一般描述如下：

General Format = array array_unique(array $array [, int $sort_flags=sort_string] )
Parameters     = array: Input array ->sort_flags:
    The second optional parameter is used to compare items as follows
         1. SORT_REGULAR - Normal
         2. SORT_NUMERIC - Numerically
         3. SORT_STRING - As
         4. string  SORT_LOCALE_STRING - As string, based on the current locale.
Return Value   = Another array without duplicate values 

示例 1：

<?php
$array=array('cricket'=>11,'football'=>11,'chess'=>2);
echo"<br/><b>Initially the values of \$array is:</b><br/>";
var_dump($array);
echo"<br/><b>After removing the duplicates:</b><br/>";
print_r(array_unique($array));
?>

输出：

Initially the values of $array is:
array(3) {
  ["cricket"] => int(11)
  ["football"] => int(11)
  ["chess"] => int(2)
}

After removing the duplicates:
Array
(
    [cricket] => 11
    [chess] => 2
)

Answer 4

试试这个：

$data = array_map('unserialize', array_unique(array_map('serialize', $data)));

输出以下内容：

Array
(
    [0] => Array
        (
            [RecipientID] => 3
            [RecipientScreenname] => Tom L
            [RecipientFirstname] => Thomas
            [RecipientEmail] => [email protected]
        )

    [2] => Array
        (
            [RecipientID] => 1
            [RecipientScreenname] => Lau T
            [RecipientFirstname] => TK
            [RecipientEmail] => [email protected]
        )
)

但我也认为你应该在数据库中实现这个。另外，检查我的其他答案和解决方案。

Answer 5

您可以使用此代码，希望它对您有所帮助。它完全可以工作：

$array = array(1,1,2,3,4,4,4,5);
$temp=array();

for($i=0; $i<=count($array); $i++)
 {

    if($array[$i] != '')
    {
        for($j=$i+1; $j<=count($array); $j++ )
        {
            if($array[$i]==$array[$j])
            {
                $array[$j] = '';
            }
            else
            {
                $temp[$array[$i]]=$array[$i];
            }

         }

    }
}

print_r($temp); 

Answer 6

您可以使用常规 php 数组来实现此目的。

$newArray = array();
foreach ($origArray as $user)
{
   $newArray[$user['RecipientID']] = $user;
}

Answer 7

请检查下面的代码，希望这对您有所帮助。

$resultArray = uniqueAssocArray($actualArray, 'RecipientID');

function uniqueAssocArray($array, $uniqueKey) {
if (!is_array($array)) {
    return array();
}
$uniqueKeys = array();
foreach ($array as $key => $item) {
    $groupBy=$item[$uniqueKey];
    if (isset( $uniqueKeys[$groupBy]))
    {
        //compare $item with $uniqueKeys[$groupBy] and decide if you 
        //want to use the new item
        $replace= false; 
    }
    else
    {
        $replace=true;
    }
    if ($replace) $uniqueKeys[$groupBy] = $item;   
}
return $uniqueKeys;

}

Answer 8

$res1       = mysql_query("SELECT * FROM `luggage` where r_bus_no='".$tour_id."' and `date1`='$date' AND `login_id`='".$_SESSION['login_id']."'");
}
/// create a array to store value
$city_arr   = array();
if(mysql_num_rows($res1)>0)
{
    while($row1 = mysql_fetch_array($res1))
    {

/// insert the value in array use the array_push function
            array_push($city_arr,$row1['r_to']);
    }

//// remove the duplicate entry in array use the array_unique function
    $a          = array_unique($city_arr);
    echo "<option value='' selected='selected'> -- Select City ---</option>";
    foreach($a as $b)
    {
    ?>
    <option value="<?php echo $b ;?>"><?php echo city($b); ?></option>
    <?php       
    }
}