$re = '/^<tr.*?>(?:<td>.*?<\/td>){2}<td>(.*?)<\/td><td>.*?<\/td><td>(.*?)<\/td>.*?<a href=".*?_(.*?)_(.*?)\.html.*$/m';
$str = '<tr><td><small>1</small></td><td>Kalisz</td><td>62-800</td><td>Poland</td><td>Greater Poland</td><td>Kalisz</td><td>Kalisz<tr><td></td><td colspan=6> <a href="/maps/browse_51.75_18.087.html" rel="nofollow"><small>51.75/18.087</small></a></td></tr>
<tr class="odd"><td><small>2</small></td><td>Piotrków Trybunalski</td><td>97-300</td><td>Poland</td><td>Łódź Voivodeship</td><td>Piotrków Trybunalski</td><td>Piotrków Trybunalski<tr class="odd"><td></td><td colspan=6> <a href="/maps/browse_51.411_19.689.html" rel="nofollow"><small>51.411/19.689</small></a></td></tr>
<tr><td><small>3</small></td><td>Toruń</td><td>87-100</td><td>Poland</td><td>Kujawsko-Pomorskie</td><td>Toruń</td><td>Toruń<tr><td></td><td colspan=6> <a href="/maps/browse_53.021_18.623.html" rel="nofollow"><small>53.021/18.623</small></a></td></tr>';
$subst = "$2;$1;$3\/$4";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php