Simple PHP keywords generator

This is a simple PHP keywords generator that receives content by parameter and returns a string with a set of keywords separated by commas and ordered by occurrences.

Optionally you can pass into the config array parameter, a text file with words that you want to avoid or an array with words that isn't important. (make sure that the words into the file are separated by commas).

If you have any improvement or suggestion, please, let me know.

Note: You can also view this article at : http://sooho.com.br


if(!function_exists('make_keywords'))
{
    /**
    * returns a set of words ordered by occurrences
    * 
* $config = array(
* 'limit_keywords_to' => integer,
* 'avoid_words' => array(),
* 'min_allowed_word_length' => integer,
* 'use_utf8_decode' => Boolean, 
* 'order_by_occurence' => Boolean
* ); 
* 
    * @param text $pContent - conteudo a transformar em keywords
    * @param array $config - (opcional) array contendo configuracoes
    * @return string - keywords
    **/
    function make_keywords( $pContent, $config = null )
    {
        # let's make an in_array case-insensitive
        if(!function_exists('in_arrayi')):
        function in_arrayi( $needle, $haystack )
        {
            return in_array( strtolower( $needle ), array_map( 'strtolower', $haystack ) );
        }
        endif;

        # initializing some default vars values
        $min_word_length = 4;
        # limit the number of output keywords
        $limit_keywords = 1000;
        # a set of disallowed words goes here
        $arr_avoid = array();
        # check if config param is set
        if(isset($config)):
        # looking for a minimum word length
        if(isset( $config['min_allowed_word_length'] )) $min_word_length = $config['min_allowed_word_length'];
        # checking for a new limit
        if(isset( $config['limit_keywords_to'] )) $limit_keywords = $config['limit_keywords_to'];
        # check if there's words to avoid
        if(isset( $config['avoid_words'] ) && ( is_array( $config['avoid_words'] ))) $arr_avoid = $config['avoid_words'];
        # maybe the avoid_words is pointing to a file! lets check!
        if(isset( $config['avoid_words'] ) && ( is_string( $config['avoid_words']) )):
        if(file_exists( $config['avoid_words'] )){
        # let's open the file in read mode
        $file_in = fopen( $config['avoid_words'],"r" );
        # let's get the filesize for the fread function
        $size = filesize( $config['avoid_words'] ) + 1;
        # getting the file content
        $file_content = fread( $file_in, $size );
        # avoid any tags
        $file_content = strip_tags( $file_content );
        # turn content into array
        # remember that the words within the file must be separated by commas
        $file_content = str_replace( " ", "", $file_content );
        $arr_words = explode(",", $file_content);
        if( is_array( $arr_words) ) 
        $arr_avoid = $arr_words;
        }
    endif;
    endif;

    # sometimes need use utf8 decode to fix some issues
    if( !isset( $config['use_utf8_decode'] ) || 
    (isset( $config['use_utf8_decode']) && 
$config['use_utf8_decode'] == TRUE ) )
        $pContent = utf8_decode($pContent);

        $pContent = strip_tags($pContent);
        # preparando conteudo para conversao
        $content = str_replace( " ", "@", $pContent );
        # remove sinais de pontuacao
        $strip_arr = array( "," ,"." ,";" ,":", "\"", "'", "“","”","(",")", "!","?" );
        $content = str_replace( $strip_arr, "", $content );
        # separa palavras, e coloca as num array
        $arr_keywords = explode( "@", $content );
        # verifica tamanho da palavra para evita artigos, pronomes, etc
        # e tambem verifica se ha palavras nao desejadas
        $key = array();
        foreach ($arr_keywords as $value) :
            if( strlen( $value ) > $min_word_length ):
                # verifica por palavras nao desejadas
                if ( in_arrayi( $value, $arr_avoid ) ) continue;
                # se potencial keyword, entao, inclui ao array
                $keys[] = $value;
            endif;
        endforeach;
        # count the number of occurrences
        $tmp = array_count_values( $keys );
        # check if needs to order the array
        if(!isset($config['order_by_occurence']) 
    || (isset($config['order_by_occurence']) 
&& $config['order_by_occurence'] == TRUE ) )
        arsort( $tmp );
        # reduces the number of elements into the array
        $ordem = array_slice( $tmp, 0, $limit_keywords );
        $arr_keywords = array();
        # gets only the keys
        foreach($ordem as $key => $value ) $arr_keywords[] = strtolower(trim( $key ));
        # implode elements with commas
        $keywords = implode( ', ', $arr_keywords );
        return $keywords;
    }
}

#example 1 ... make it as simple as possible
echo make_keywords( "Please make me some cool keywords, with the following text and make me happy!" );

echo "
";

#example 2 ... using the config param
$config = array(
'limit_keywords_to' => 100,
'avoid_words' => array( "please","avoid","select","the","words","into","this","array","as","keywords","thanks" ),
'min_allowed_word_length' => 4,
'use_utf8_decode' => FALSE, 
'order_by_occurence' => FALSE
);

echo "
";

echo make_keywords( 
"Please make me some cool keywords, with the following text and make me happy!",
$config
);

echo "
";

# example 3 ... avoid_words into a text file
# please, make sure that the words within the file is separated by commas
$config = array(
'avoid_words' => 'avoid_these_words.txt'
);
$content = "Please make me some cool keywords, with the following text and make me happy!";
echo make_keywords( $content, $config );