Comparing two lists of email addresses with PHP

[ionicle]

Hey again, everybody.

 

Need help with the solution of yet another task related to php.

 

I have two lists of email addresses - List 1 and List 2, so to say. The entire contents of List 2 is a part of List 1.

 

I would like for PHP to compare both lists and erase all the email addresses out of List 2, that are contained in List 1, plus all the email addresses, located at every domain name, listed within List 2.

 

For instance:

 

List 1:

 

brym@yahoo.com

gargamel@yahoo.com

grungel@gmail.com

shushlek@hotmail.com

gushterlqk@aol.com

shuslica@web.de

 

 

List 2:

 

brym@yahoo.com

grungel@gmail.com

 

 

After processing's completed, List 1 should look like this:

 

List 1:

 

shushlek@hotmail.com

gushterlqk@aol.com

shuslica@web.de

 

How would I go about doing that?

[cyberRobot]

Have you looked into array_diff():

http://us2.php.net/manual/en/function.array-diff.php

[ionicle]

That looks pretty convenient! Thing is, I not only need the entire List 2 to be removed from List 1, but also have all email addresses from List 1, matching with all domain names from List 2, be removed from List 1. 

 

array_diff() wouldn't help with that, I guess.

Edited November 22, 2013 by ionicle

[cyberRobot]

Does array_diff() return the desired results? If so, you could assign the results back to the variable holding list 1.

[JIXO]

Try this

<?php
    // LIST 1
    $list1 = array(
        "brym@yahoo.com",
        "gargamel@yahoo.com",
        "grungel@gmail.com",
        "shushlek@hotmail.com",
        "gushterlqk@aol.com",
        "shuslica@web.de"
    );
    // LIST 2
    $list2 = array(
        "brym@yahoo.com",
        "grungel@gmail.com"
    );
    
    function extractUnwantedDomains($list2) {
        $list2Domains = array();
        foreach($list2 as $email) {
            $atPosition = strripos($email, '@');
            $dotPosition = strripos($email, '.', $atPosition + 1);
            $list2Domains[] = substr($email, ($atPosition + 1), ($dotPosition - 1) - ($atPosition));
        }
        return($list2Domains);
    }
    
    
    
    function extractFinalList($list1, $list2) {
        $finalList = array();
        $difference = array_diff($list1, $list2);
        $unwantedDomains = extractUnwantedDomains($list2);
        foreach($difference as $email) {
            foreach($unwantedDomains as $domain) {
                if(preg_match("/{$domain}/", $email)) {
                    continue(2);
                }
            }
            $finalList[] = $email;
        }
        return($finalList);
    }
    
    $finalList = extractFinalList($list1, $list2);
    var_dump($finalList);

Edited November 22, 2013 by JIXO

[cyberRobot]

Nevermind....I just re-read the question and noticed my solution doesn't quite meet your needs. 

Edited November 22, 2013 by cyberRobot

[cyberRobot]

You could try using array_diff() to get the difference. And then adapt the solution provided a few days ago to get unique domains:

http://forums.phpfreaks.com/topic/284098-pick-a-random-email-address-out-of-a-maillist/?do=findComment&comment=1459187

[mac_gyver]

just satisfying your second condition of removing all entries with the same domains found in the second list will remove the specific emails in the first condition.

 

the quickest code would be to preprocess the arrays of addresses so that you have an array of arrays, where the main key is the domain name (shown in pseudo code form, not the actual array) -

 

$array1['yahoo.com'] = array(brym@yahoo.com,gargamel@yahoo.com)

$array1['gmail.com'] = array(grungel@gmail.com)

$array1['hotmail.com'] = array(shushlek@hotmail.com)

...

 

$array2 ....

 

then (untested), you should be able to use array_diff() and the main key values in the second list will remove all the corresponding domain entries in the first list.

Edited November 22, 2013 by mac_gyver

[mac_gyver]

using array_diff_key() -

 $list1 = array(
"brym@yahoo.com",
"gargamel@yahoo.com",
"grungel@gmail.com",
"shushlek@hotmail.com",
"gushterlqk@aol.com",
"shuslica@web.de"
);

$list2 = array(
"brym@yahoo.com",
"grungel@gmail.com"
);

$array1 = array();
foreach($list1 as $email){
    list($name,$domain) = explode('@',$email);
    if(!isset($array1[$domain])){$array1[$domain] = array();}
    $array1[$domain][] = $email;
}

$array2 = array();
foreach($list2 as $email){
    list($name,$domain) = explode('@',$email);
    if(!isset($array2[$domain])){$array2[$domain] = array();}
    $array2[$domain][] = $email;
}

$result = array_diff_key($array1,$array2);

$final = array();
foreach($result as $arr){ // there should be a way to do this without a loop...
    $final = array_merge($final,$arr);
}

echo '<pre>';
print_r($final);

[ionicle]

Turns out JIXO's code works. For some reason though, when I load up a large number of email addies in the arrays, it screws up and spits out a blank result. No clue why.

 

I got another reply on Stackoverflow:

 

 

 
<?php
 
function domain($email){
$x=explode('@',$email);
return $x[1];
}

$list1=array("brym@yahoo.com","gargamel@yahoo.com","grungel@gmail.com","shushlek@hotmail.com","gushterlqk@aol.com","shuslica@web.de");//first list
$list2=array("brym@yahoo.com","grungel@gmail.com");//second list
$black_domains=array();
foreach($list2 as $l2){
$black_domains[]=domain($l2);
}
$new_list1=array();
foreach($list1 as $l1){
$domain=domain($l1);
if(!in_array($domain,$black_domains)){
$new_list1[]=$l1;
};
}

print_r($new_list1); //this gives new list
 
?>
 

 

 

That one works like a charm, even with very large lists.