What is Keyword Density and how to create a script in PHP?

Question

I am working on a project where I have to find out the keyword density of thepage on the basis of URL of that page. I googled a lot but no help and scripts were found, I found a paid tool http://www.selfseo.com/store/_catalog/php_scripts/_keyword_density_checker_php_script

But I am not aware actually what "keyword Density of a page" actually means? and also please tell me how can we create a PHP script which will fetch the keyword density of a web page.

Thanks

Answer 1

"Keyword density" is simply the frequency that the word occurs given as a percentage of the total number of words. The following PHP code will output the density of each word in a string, $str. It demonstrates that keyword density is not a complex calculation, it can be done in a few lines of PHP:

<?php
$str = "I am working on a project where I have to find out the keyword density of the page on the basis of URL of that page. But I am not aware actually what \"keyword Density of a page\" actually means? and also please tell me how can we create a PHP script which will fetch the keyword density of a web page.";

// str_word_count($str,1) - returns an array containing all the words found inside the string
$words = str_word_count(strtolower($str),1);
$numWords = count($words);

// array_count_values() returns an array using the values of the input array as keys and their frequency in input as values.
$word_count = (array_count_values($words));
arsort($word_count);

foreach ($word_count as $key=>$val) {
    echo "$key = $val. Density: ".number_format(($val/$numWords)*100)."%<br/>\n";
}
?>

Example output:

of = 5. Density: 8%
a = 4. Density: 7%
density = 3. Density: 5%
page = 3. Density: 5%
...

To fetch the content of a webpage you can use file_get_contents (or cURL). As an example, the following PHP code lists all keywords above 1% density on this webpage:

<?php
$str = strip_tags(file_get_contents("http://stackoverflow.com/questions/819166"));

$words      = str_word_count(strtolower($str),1);
$word_count = array_count_values($words);

foreach ($word_count as $key=>$val) {
    $density = ($val/count($words))*100;
    if ($density > 1)
        echo "$key - COUNT: $val, DENSITY: ".number_format($density,2)."%<br/>\n";
}
?>

I hope this helps.

Answer 2

Or you can try this: http://code.eyecatch-up.de/?p=155
Update: Relocated the class to http://code.google.com/p/php-class-keyword-density-check/

<?php
include 'class/class.keywordDensity.php';             // Include class  

$obj = new KD();                                      // New instance
$obj->domain = 'http://code.eyecatch-up.de';          // Define Domain
print_r ($obj->result()); 
?>

above code returns:

Array
(
    [0] => Array
        (
            [total words] => 231
        )

    [1] => Array
        (
            [keyword] => display
            [count] => 14
            [percent] => 6.06
        )
and so on...

works with local and remote files.