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); ?> |
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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