Extract words from string with preg_match_all

Question

I'm not good with regex but i want to use it to extract words from a string.

The words i need should have minimum 4 characters and the provided string can be utf8.

Example string:

Sus azahares presentan gruesos pétalos blancos teñidos de rosa o violáceo en la parte externa, con numerosos estambres (20-40).

Desired output:

Array(
    [0] => azahares
    [1] => presentan
    [2] => gruesos
    [3] => pétalos
    [4] => blancos
    [5] => teñidos
    [6] => rosa
    [7] => violáceo
    [8] => parte
    [9] => externa
    [10] => numerosos
    [11] => estambres
)

Answer 1

When you use the u modifier, you can use the following pattern (demo):

preg_match_all('(\w{4,})u', $string, $matches);
print_r($matches[0]);

The u modifier means:

u (PCRE_UTF8): This modifier turns on additional functionality of PCRE that is incompatible with Perl. Pattern strings are treated as UTF-8. This modifier is available from PHP 4.1.0 or greater on Unix and from PHP 4.2.3 on win32. UTF-8 validity of the pattern is checked since PHP 4.3.5.

Answer 2

that should do the job for you

function extractCommonWords($string) {
    $stopWords = array('i','a','about','an','and','are','as','at','be','by','com','de','en','for','from','how','in','is','it','la','of','on','or','that','the','this','to','was','what','when','where','who','will','with','und','the','www');

    $string = preg_replace('/\s\s+/i', '', $string); //echo $string, "<br /><br />"; // replace whitespace
    $string = trim($string); // trim the string
    $string = preg_replace('/[^a-zA-Z0-9 -_]/', '', $string); // only take alphanumerical characters, but keep the spaces and dashes too…
    $string = strtolower($string); // make it lowercase

    preg_match_all('/([a-zA-Z]|\xC3[\x80-\x96\x98-\xB6\xB8-\xBF]|\xC5[\x92\x93\xA0\xA1\xB8\xBD\xBE]){4,}/', $string, $matchWords);
    $matchWords = $matchWords[0];

    foreach($matchWords as $key => $item) {
        if($item == '' || in_array(strtolower($item), $stopWords) || strlen($item) <= 3) {
            unset($matchWords[$key]);
        }
    }

    $wordCountArr = array();
    if(is_array($matchWords)) {
        foreach($matchWords as $key => $val) {
            $val = strtolower($val);
            if(isset($wordCountArr[$val])) {
                $wordCountArr[$val]++;
            } else {
                $wordCountArr[$val] = 1;
            }
        }
    }

    arsort($wordCountArr);
    $wordCountArr = array_slice($wordCountArr, 0, 10);
    return $wordCountArr;
}

Answer 3

Try this one:

$str='Sus azahares presentan gruesos pétalos blancos teñidos de rosa o violáceo en la parte externa, con numerosos estambres (20-40).';
preg_match_all('/([^0-9\s]){4,}/i', $str, $matches);
echo '<pre>';
var_dump($matches);
echo '</pre>';

Answer 4

This works if the words to look for are UTF-8 (at least 4 chars long, as per specs), consisting of alphabetic characters of ISO-8859-15 (which is fine for Spanish, but also for English, German, French, etc.):

$n_words = preg_match_all('/([a-zA-Z]|\xC3[\x80-\x96\x98-\xB6\xB8-\xBF]|\xC5[\x92\x93\xA0\xA1\xB8\xBD\xBE]){4,}/', $str, $match_arr);
$word_arr = $match_arr[0];

Answer 5

You can use the regex below for simple strings. It will match any non-whitespace characters with min length = 4.

preg_match_all('/(\S{4,})/i', $str, $m);

Now $m[1] contains the array you want.

Update:

As Gordon said, the pattern will also match the '(20-40)'. The unwanted numbers can be removed using this regex:

preg_match_all('/(\pL{4,})/iu', $str, $m);

But I think it only works if PCRE is compiled with UTF-8 support. See PHP PCRE (regex) doesn't support UTF-8?. It works on my computer though.

Answer 6

$string = Sus azahares presentan gruesos pétalos blancos teñidos de rosa o violáceo en la parte externa, con numerosos estambres

$words = explode(' ', $string);
echo $words[0];
echo $words[1];

and so on