Spam emails

[danielbala]

Hi..

 

I want to implement a program for identifying spam emails using an algorithm naive bayes

in php..

 

How to implement this ..can any one help me..

 

Thx in advance

[Adam]

Mail servers are generally written in lower-level languages like C and Java. What mail server are you using? I very much doubt it's PHP.

[danielbala]

..Im not using  any mail server..i want to write a program for identifying spam emails using naive

bayes algorithm...i want to try it using php

 

i just took this code from google..i dont know whether we should create DB table or any forms with fields??

 

<?php
class SpamChecker {
  public $dbh = null;

  function trainFilter($text,$isspam=true) {
    if(is_null($this->dbh)) {
      throw new Exception("Database connection is null");
    }
    $query = $this->dbh->prepare
      ('select totalsid,totalspam,totalham FROM totals;');
    $query->execute();
    $result = $query->fetchAll();
    $totalsid = $result[0]['totalsid'];
    $totalspam = $result[0]['totalspam'];
    $totalham = $result[0]['totalham'];

    if($isspam){
      $totalspam++;
      $query = $this->dbh->prepare
        ('update `totals` set totalspam=? where totalsid=1 limit 1;');
      $insert = $query->execute(array($totalspam));
    }
    else {
      $totalham++;
      $query = $this->dbh->prepare
        ('update `totals` set totalham=? where totalsid=1 limit 1;');
      $insert = $query->execute(array($totalham));
    }
    
    $text = preg_replace('/\W+/',' ',$text);
    $text = preg_replace('/\s\s+/',' ',$text);
    $text = strtolower($text);
    $temparray = explode(' ',$text);

    $gettokenquery = $this->dbh->prepare
      ('select `spamid`,`spamcount`,`hamcount` from spam 
        where token=? limit 0,1;');

    foreach($temparray as $token) {
      $gettokenquery->execute(array($token));
      $result = $gettokenquery->fetchAll();

      if(count($result) == 0) {
        if($isspam) {
          $query = $this->dbh->prepare
            ("insert into `spam` (`token`,`spamcount`,`hamcount`,
              `spamrating`) values (?,'1','0','1');");
          $insert = $query->execute(array($token));
        }
        else {
          $query = $this->dbh->prepare
            ("insert into `spam` (`token`,`spamcount`,`hamcount`,
              `spamrating`) values (?,'0','1','0');");
          $insert = $query->execute(array($token));
        }
      }
      else { // Already exists in the database
        $spamcount = $result[0]['spamcount'];
        $hamcount = $result[0]['hamcount'];

        if($isspam){
          $spamcount++;
        }
        else {
          $hamcount++;
        }

        $hamprob = 0;
        $spamprob = 0;
        if($totalham != 0){
          $hamprob = $hamcount/$totalham;
        }
        if($totalspam != 0) {
          $spamprob = $spamcount/$totalspam;
        }
        if($hamprob+$spamprob != 0) {
          $spamrating = $spamprob/($hamprob+$spamprob);
        }
        else {
          $spamrating = 0;
        }

        $query = $this->dbh->prepare
          ("update `spam` set `spamcount`=?, `hamcount`=?,
            `spamrating`=? where token=? limit 1;");
        $query->execute(array($spamcount,$hamcount,
                              $spamrating,$token));
      }
    }
  }

  function checkSpam($text) {
    if(is_null($this->dbh)) {
      throw new Exception("Database connection is null");
    }

    $text = preg_replace('/\W+/',' ',$text);
    $text = preg_replace('/\s\s+/',' ',$text);
    $text = strtolower($text);
    $temparray = explode(' ',$text);

    $gettokenquery = $this->dbh->prepare
      ('select `token`,`spamrating` from spam where token=? limit 0,1;');
    $spamratings = array();
    foreach($temparray as $token) {
      $gettokenquery->execute(array($token));
      $result = $gettokenquery->fetchAll();
      $spamrating = $result[0]['spamrating'];
      if($spamrating == ''){
        $spamrating = 0.4;
      }
      $spamratings[] = $spamrating;
    }

    $a = null;
    $b = null;

    foreach($spamratings as $rating) {
      $rating = max($rating,0.01);
      $a = is_null($a) ? (float)$rating : $a * $rating;
      $b = is_null($b) ? 1-(float)$rating : $b * (1-(float)$rating);
    }
    $spam = (float)0;
    if((float)((float)$a+(float)$b) != 0) {
      $spam = (float)$a/(float)((float)$a+(float)$b);
    }
    return $spam;
  }

  function resetFilter() {
    if(is_null($this->dbh)) {
      throw new Exception("Database connection is null");
    }
    $trun = $this->dbh->prepare('TRUNCATE TABLE `spam`;');
    $trun->execute();
    $trun = $this->dbh->prepare
              ('update totals set totalspam=0, totalham=0 limit 1;');
    $trun->execute();
  }
}
?>
Hide details
Change log
r31 by bboyte01 on May 23, 2010   Diff
Update to remove issues with divide by
zero errors.
Go to: 	
Double click a line to add a comment
Older revisions
r28 by bboyte01 on Apr 14, 2010   Diff 
r27 by bboyte01 on Feb 18, 2010   Diff 
r26 by bboyte01 on Feb 18, 2010   Diff 
All revisions of this file
File info
Size: 4111 bytes, 141 lines
View raw file
File properties
svn:mergeinfo

[Adam]

Okay, we're not going to go through some random code you found on Google and show you how to use it. Though yes, you would need to set-up all the relevant database tables and actually write the 'glue' code that would make use of that class.

 

Do you actually understand the Naive Bayes algorithm, and of course Bayes theorem that it's based on? Have you researched the common ways in which spam email is identified?