Alex M's Blog » PHP

Google Charts API Extended Encode Scaling

Alex M — Thu, 17 Sep 2009 04:51:42 +0000

I’ve recently been playing with the Google Charts API for a project, and ran into a problem with graph scaling when using extended encoding.

The problem was that there was no scaling on the graph when using extended encoding, so values of the graph were plotted with the y-axis having a maximum value of 4095.

This meant that smaller values look insignificant on the graph, not to mention all the wasted space. The solution I came up with is to scale the data so it fills the chart appropriately.

The PHP code I came up with is below, and also extends on a function written by Ben Dodson.

< ?php
/*
 * Returns a scaled value.
 *
 * @param    value     Int to scale
 * @param    max       Maximum int in array to calculate scale value
 * @param    scale     The int to scale value to
 * @return             Scaled value
 * @author             Alex McKenzie 
 */
function scale_value($value, $max, $scale = 4095) {
	return ($value/$max) * $scale;
}
 
/**
 * Retunrs an extended encoded string for use with Google Charts API.
 *
 * Modified function - original by Ben Dodson (http://bendodson.com/blog/2008/02/28/google-extended-encoding-made-easy/).
 *
 * @param    array     Array of values to encode
 * @param    scale     Whether to scale the values
 * @return             Extended encoded string
 * @author             Alex McKenzie 
 */
function array_to_extended_encoding($array, $scale = 'yes') {
    $characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-.';
 
    // Scale values before encoding if required.
    if ($scale == 'yes') {
        $max = max($array);
        $scaled_array = array();
        foreach($array as $value) {
            array_push($scaled_array, scale_value($value, $max));
        }
        $array = $scaled_array;
    }
 
    // Encode values in array.
    $encoding = '';
    foreach ($array as $value) {
        $first = floor($value / 64);
        $second = $value % 64;
        $encoding .= $characters[$first] . $characters[$second];
    }
    return $encoding;
}?>alex>

Now using some sample data, we can see the difference scaling makes in the following two examples:

The graphs above were generated with the following code:

< ?php
$graph = array(200,300,200,250,350,150,100);
?>
 
array_to_extended_encoding($graph, $scale = 'no')?/>" alt="No scalling" />
http://chart.apis.google.com/chart?cht=bvs&chs=200x150&chd=e:" alt="Scalling" />

Uppercase first word in a string or sentence

Alex M — Sun, 24 May 2009 11:36:30 +0000

I have just had a task which requires making the first word of a string uppercase. I have come up with quite an easy and simple solution and thought I would share it with you.

An example input string might look like “HELLO world. This is a test.” The required output is “Hello world. This is a test.”

Below is a function which will help you achieve this:

function uc_first_word($string) {
    $s = explode(' ', $string);
    $s[0] = ucfirst(strtolower($s[0]));
    $s = implode(' ', $s);
    return $s;
}

Now I know this function isn’t full proof, and assumes that the string you are passing actually contains words. If the first word was a roman numeral for example, this function would not work (ie VI would become Vi).

Usage of this function is quite easy:

1	$string = uc_first_word('HELLO world. This is a test.');

I hope that this might help someone searching for a similar solution.

Deleting array element by key in PHP

Alex M — Thu, 26 Mar 2009 05:05:12 +0000

I had to think about this one for a while, as I was trying to delete an array element which I knew the key of (and there is no array_delete() function).

1	e.g. $array['something'] = 'value';

Turns out deleting the value is easy using the unset() command.

1	unset($array['something']);

$array['something'] no longer exists. Hope this helps someone else.