Pyrocket and Ubuntu

I have a great USB rocket launcher, it’s more useful than a computer mouse most of the time actually. I spotted a moth on the roof the other day, and hadn’t installed pyrocket on this computer yet.

A quick apt-get install pyrocket is all it takes to solve that though, right? No such luck.

Apparently, the quality control in the Ubuntu repos are such that this package has been broken for several months now, despite the dependency issue being fixed by an upstream fork.

So this is the error you get at the moment anyway:

Traceback (most recent call last):
  File "/usr/bin/pyrocket", line 17, in 
    from rocket_frontend import RocketWindow
  File "/usr/lib/pymodules/python2.7/", line 11, in <module>
    from rocket_webcam import VideoWindow
  File "/usr/lib/pymodules/python2.7/", line 2, in <module>
    from opencv import cv, highgui
ImportError: No module named opencv

The solution, beyond complaining about it, is to read the bug report here and do this:

git clone
cd pyrocket/src

But the moth had escaped by then.

Changing the IP address on a Cisco switch

Cisco switches are a bit cryptic, but well documented. You can generally do just about anything with enough patience and Googling, but even simple configuration tasks can be difficult if you’re not familiar with the interface.

These are my 3 tips to configuring Cisco devices:

1. telnet
Always telnet or SSH to the switch to log on. Don’t use configuration utilities or a web interface, because everything that turns up on Google refers to the command-line interface.
2. enable
All of the fun options are hidden by default. Make liberal use of enable to do the serious work.
3. ?
Pressing ? pops up a list of ways you can finish off the current command.

For example: IP settings

The first step when moving around a used switch is to set it up for a different network. Here is where you will find the IP config:/p>

Log in:

telnet 10.1.x.x

Now enable the admin options:

Password: (type in your password)

Note that the prompt has changed from < to #. We can now change the IP and subnet mask of the switch:

interface vlan 1
ip address 10.1.x.x 255.255.x.x

Converting Numbers To Words in PHP

This is a straightforward coding task. I’m working on some maths code in PHP, and need a function to output “twenty-five” for 25, “fifteen” for 15, etc. A quick google search pulled up a neat little PEAR package which can do this.

The results weren’t as flash as I’d hoped though. We ended up with this:

894: eight hundred ninety-four

So it turns out that the PEAR class doesn’t print commas or the word ‘and’ in its numbers. We will be feeding our numbers to festival, and also using them for maths questions. Those pesky ands and commas are a must for this project, so this is not good enough:

9539: nine thousand five hundred thirty-nine

Instead, I need:

9539: nine thousand, five hundred and thirty-nine

I found some commented out code, and tried my own modifications, but it wasn’t working right, so I scrapped the PEAR class and started from scratch, using Wikipedia to populate the lists:

The results were perfect. It took about 300 lines to replace the class, and it handles ordinal numbers too. (‘1st’ = ‘first’, ‘100th = one hundredth’, etc). I ditched the currency feature.

To download the replacement class, click here.

It’s simple to use, just express ridiculous numbers or long decimals as strings to avoid errors. See this example for features:

 // one
echo Numbers_Words::toWords(1); newline();

 // two
echo Numbers_Words::toWords(2); newline();

 // twenty-five
echo Numbers_Words::toWords(25); newline();

 // one thousand
echo Numbers_Words::toWords(1000); newline();

 // one thousand and one
echo Numbers_Words::toWords(1001); newline();

 // one hundred thousand and one
echo Numbers_Words::toWords(100001); newline();

 // one hundred and twenty-three million, four hundred and fifty-six thousand, seven hundred and eighty-nine
echo Numbers_Words::toWords("123 456 789"); newline();

 // thirty-six point nine seven
echo Numbers_Words::toWords(36.97); newline();

 /* nine novemvigintillion, eight hundred and seventy-two octovigintillion, three hundred and fourty-eight septemvigintillion,
	nine hundred and seventy-two sesvigintillion, four hundred and ninety-two quinquavigintillion,
	three hundred and eighty-four quattuorvigintillion, nine hundred and two tresvigintillion,
	three hundred and eighty-four duovigintillion, two hundred and ninety unvigintillion, three hundred and eighty-four vigintillion,
	two hundred and ninety novemdecillion, three hundred and fourty-two octodecillion, five hundred and sixty-three septendecillion,
	four hundred and seventy-five sexdecillion, six hundred and thirty-four quindecillion, eight hundred and fifty-seven quattuordecillion,
	four hundred and fifty-seven tredecillion, three hundred and fourty-nine duodecillion, eight hundred and fifty-seven undecillion,
	two hundred and thirty-four decillion, five hundred and twenty-three nonillion, five hundred and thirty-four octillion,
	eight hundred and fifty-three septillion, two hundred and ninety sextillion, four hundred and seventy-eight quintillion,
	two hundred and ninety quadrillion, three hundred and fourty-seven trillion, two hundred and thirty-eight billion,
	nine hundred and fourty-six million, five hundred and thirty-eight thousand, four hundred and seventy-six */
echo Numbers_Words::toWords("9872348972492384902384290384290342563475634857457349857234523534853290478290347238946538476"); newline();

 // seventeenth
echo Numbers_Words::toWords("17th"); newline();

 // eight hundred and sixty-third
echo Numbers_Words::toWords("863rd"); newline();

 // negative seventy-eight point four
echo Numbers_Words::toWords("-78.4"); newline();

function newline() {
	echo "<br />n";

Using correct strings makes synthetic voices much less annoying, and nobody can complain about bad maths questions. :)

Loading OEIS integer sequences

To show that interpreted languages can be fast when used well, I’m posting this example.

Take the On-line Encyclopedia of Integer Sequences database, which is a collection of integer sequences. That means lists of numbers. You can get a file from, which contains the first few numbers of each sequence. Today’s file extracts to about 38MB.

Now I need to do lookups in this file for a program I’m writing, and that program is in PHP. We want to know some sequences based on their A-number, like this:

$primes = oeis("A000040");
$fibonacci = oeis("A000045");

If we’re smart about it, then even a large file can be parsed in fractions of a second. Here’s how we do it:

/* This code needs an extract of the OEIS database to operate.
	I got it from
	Just extract that to this folder for lookups */
function oeis($number) {
	/* Return an array of values based on a sequence's OEIS number */
	$number = strtoupper($number);
	$fp = fopen("stripped", "r");
	while($ln = fgets($fp)) { /* Find this sequence and break the loop */
		if(substr($ln, 0, strlen($number) + 1) == $number." ") {
			$res = $ln;
	/* Exit if we haven't got anything */
	if(!isset($res)) { return false; }
	$rv = explode(" ", $ln); /* Split lines into left and right of space */
	$ln = trim($rv[1]);
	$ln = substr($ln, 1, strlen($ln)-2); /* Slices off extra commas on sides */
	$rv = explode(",", $ln); /* Split by commas */
	return $rv;

Note that we don’t use explode() until after we have found the line we need, and also note that file_get_contents() is not used at all. (Multi-megabyte strings will bog you down in any language).

Parsing Asterisk Configuration

If you are writing for Asterisk PBX, you may feel the need to create a public telephone directory.

Today we’ve been putting together Phonebook, a web-based phonebook which pulls data from an asterisk server. We used JQTouch for the interface, with PHP to process data files. We also use a CSV file exported from our hosted gmail to ensure that people’s names are spelled correctly.

The configuration

Asterisk’s configuration files are INI-like, and you’ll find them in /etc/asterisk/ on most systems. Just one important thing though, asterisk lets you use brackets ( ) in caller-IDs, etc, which will cause PHP’s parse_ini_file() function to fizzle out and die due to an alleged syntax error.

To save yourself some trouble, use this little class I wrote, which will load INI data into an associative array:

class ns_ini_parser {
	/* Mike's non-standard INI parser for asterisk files.
		Note that PHP's parse_ini_file will die with a syntax error on key = value (bracket), which is unacceptable */

	function parse_string($string) {
		$lines		= explode("n", $string);
		$section	= "0";
		$result		= array();
		foreach($lines as $line) {
			$line = trim($line);
			if($line == "" || substr($line, 0,1) == ";") {
				/* Comment, no action */
			} elseif(substr($line, 0,1) == "[") {  /* [section] */
				$l		  = strlen($line);
				$line		  = trim(substr($line, 1, $l - 2));	/* Strip brackets */
				$section	  = $line;
				if(!isset($result[$section])) {
					$result[$section] = array();
			} else {				/* key = val */
				$parts = explode("=", $line);
				$key = trim($parts[0]);	/* The key is everything left of the equal */
				unset($parts[0]);	/* Got that, unset it */
				$val = trim(join("=", $parts));	/* Value is everything on the righht */
				$result[$section][$key] = $val;
		return $result;

	function parse_file($path) {
		$string = file_get_contents($path);
		return $this -> parse_string($string);

The example usage below will list user’s extensions next to their caller ID, which you could use for a web phonebook:

/* Example PHP code to parse asterisk configuration */
$config_parser = new ns_ini_parser;
$users  = $config_parser -> parse_file("/etc/asterisk/users.conf");

foreach($users as $id => $user) {
	if(is_numeric($id)) { /* Only show numbers, not other sections */
		echo "<a href="tel:$id">$id</a> ".$user['fullname']."<br />";

I don’t think it gets easier than that! I’ll post the rest once you can manage the contacts as well.