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Home php教程 php手冊 如何利用php數(shù)組對百萬數(shù)據(jù)進行排重

如何利用php數(shù)組對百萬數(shù)據(jù)進行排重

Jun 13, 2016 am 11:35 AM
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如何利用php數(shù)組對百萬數(shù)據(jù)進行排重

在平時的工作中,經常接到要對網站的會員進行站內信、手機短信、email進行群發(fā)信息的通知,用戶列表一般由別的同事提供,當中難免會有重復,為了避免重復發(fā)送,所以我在進行發(fā)送信息前要對他們提供的用戶列表進行排重,下面我以uid列表來講講我是如何利用php數(shù)組進行排重的。

假如得到一個uid列表,數(shù)量在百萬行以上,格式如下:

10001000

10001001

10001002

................

10001000

................

10001111

其實利用php數(shù)組的特性,很好進行排重,我們先來看一下php數(shù)組的定義:PHP 中的數(shù)組實際上是一個有序映射。映射是一種把 values 關聯(lián)到 keys 的類型。此類型在很多方面做了優(yōu)化,因此可以把它當成真正的數(shù)組,或列表(向量),散列表(是映射的一種實現(xiàn)),字典,集合,棧,隊列以及更多可能性。數(shù)組元素的值也可以是另一個數(shù)組。樹形結構和多維數(shù)組也是允許的。

在php的數(shù)組中,鍵(keys)也稱為索引,具有唯一性,我們正可以利用這一特性進行排重,示例代碼如下:

<?php
//定義一個數(shù)組,用于存放排重后的結果
$result = array();
//讀取uid列表文件
$fp = fopen('test.txt', 'r');

while(!feof($fp))
{
    $uid = fgets($fp);
    $uid = trim($uid);
    $uid = trim($uid, "r");
    $uid = trim($uid, "n");

    if($uid == '')
    {
        continue;
    }
    //以uid為key去看該值是否存在
    if(empty($result[$uid]))
    {
        $result[$uid] = 1;
    }
}

fclose($fp);

//將結果保存到文件
$content = '';
foreach($result as $k => $v)
{
    $content .= $k."n";
}
$fp = fopen('result.txt', 'w');
fwrite($fp, $content);
fclose($fp);
?>
20多行代碼,就可以對百萬以上的數(shù)據(jù)進行排重,效率也不錯,非常實用。手機號、email,也可以采用這種方式進行排重。

還有,這可方法還可以用于兩個文件進行排重的工作,如果你有兩個uid列表文件,格式和上面的uid列表一樣,示例程序如下:

<p><table cellspacing="0" cellpadding="6" width="95%" align="center" border="0" style="border-right: #0099cc 1px solid; table-layout: fixed; border-top: #0099cc 1px solid; border-left: #0099cc 1px solid; border-bottom: #0099cc 1px solid"><tbody><tr><td bgcolor="#ddedfb" style="word-wrap: break-word"><pre class="code">
<?php
//定義數(shù)組,用于存放排重后的結果
$result = array();
//讀取第一個uid列表文件,放入$result_1
$fp = fopen('test_1.txt', 'r');

while(!feof($fp))
{
    $uid = fgets($fp);
    $uid = trim($uid);
    $uid = trim($uid, "r");
    $uid = trim($uid, "n");

    if($uid == '')
    {
        continue;
    }
    //以uid為key寫入$result,如有重復就會覆蓋
    $result[$uid] = 1;
}

fclose($fp);

//讀取第二個uid列表文件,并進行排重操作
$fp = fopen('test_2.txt', 'r');
while(!feof($fp))
{
    $uid = fgets($fp);
    $uid = trim($uid);
    $uid = trim($uid, "r");
    $uid = trim($uid, "n");

    if($uid == '')
    {
        continue;
    }
    //以uid為key去看該值是否存在
    if(empty($result[$uid]))
    {
        $result[$uid] = 1;
    }
}
fclose($fp);

//$result里保存的就排重以后的結果,可以輸出到文件,代碼省略
?>

?

仔細想想,不難發(fā)現(xiàn),利用數(shù)組的這一特性還可以解決我們工作中的更多問題。

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