Archive for the ‘Programming’ Category

In the past, people have hassled me to make it easier for them to install my applications and libraries on OS X. I’m not very skilled with OS X, and searching for how to do this task took some time. I’ve made a script that does this in a modular way for Python. Specifically, this article describes the process of making a Python module or extension installer for OS X, similar to the Python installer for Windows.

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I just released pygooglechart 0.2.1. It has several bug fixes and minor additions, but the major change is that it now supports QR codes. You can quite easily create a QR code with pygooglechart as you can see below.

from pygooglechart import QRChart

# Create a 125x125 QR code chart
chart = QRChart(125, 125)

# Add the text
chart.add_data('Hello, World!')

# "Level H" error correction with a 0 pixel margin
chart.set_ec('H', 0)

# Download
chart.download('qr-hello.png')

This will download a png from the URL:

http://chart.apis.google.com/chart?cht=qr&chs=125×125&chl=Hello%2C%20World%21&chld=H|0

The image downloaded looks like this:

QR codes are new to me. I’ve only seen a QR code on a bus stop advertisement once in Sydney but I’m sure more will pop up.

I wrote an application to generate a wireless (802.11) heat map based on signal strength. The reason for it was to find the best place/area (for my laptop) to be with the highest signal strength. Below is a screenshot of the application (with the ESSID and BSSID removed for security reasons).

This heat map has about 100 samples in it, which are shown as white dots. There is a balcony at the top of the image and the common office area on the right, which was drawn by hand (hence the waviness). As you can see it has pinpointed the location of the access point in the red area.

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Last week I quietly released pycallgraph 0.5.1 with some outstanding bugs fixed and preparation for it to be a Debian package.

Cython is an easy way to create Python extensions in “pseudo-Python” without having to deal with the verboseness of the Python API. It also does not rely on you knowing much of the C language. Cython is based on Pyrex which I have some experience with. This tutorial shows you how to convert a simple Python module to a Python extension.

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I decided to make a CAPTCHA plugin for Trac called TracRecaptchaPlugin, to stop spammers using the ticket system. There is an existing Trac plugin to fight spammers, but it still lets through many automated spammers.

The plugin uses the reCAPTCHA service and is serving me well so far. Here’s how it looks within the template:

This is my first publicly released Trac plugin so I’m unsure how it’ll perform out there, so feedback is welcome.

I released pygooglechart 0.2.0 this afternoon after several months of patches coming in to add features and fix bugs. The main addition to pygooglechart is automatic data scaling, which is turned on by default. You can also specify the scale range manually:

chart = SimpleLineChart(width, height, x_range=(0, 100), y_range=(0, 100))

Other features are the new API chart types and options. There are 3 new chart types: Map, Google-o-Meter and Radar. Here is an example of using the Map chart type:

import pygooglechart as gc

chart = gc.MapChart(440, 220)
chart.set_colours(('AAAAAA', '30A030', 'A0C030'))
chart.set_codes(['AU', 'US', 'CA', 'BR', 'NZ'])
chart.add_data([1, 0.5, 0.7, 0.3, 0.1])
chart.download('map.png')

Produces the URL:
http://chart.apis.google.com/chart?cht=t&chs=440×220&chd=s:9frSG&chco=AAAAAA,30A030,A0C030&chtm=world&chld=AUUSCABRNZ

And the image:

The Google-o-meter has a funny name. Here is an example of its usage:

import pygooglechart as gc

chart = gc.GoogleOMeterChart(440, 220, y_range=(0, 10))
chart.set_pie_labels(['Awesome'])
chart.add_data([8])
chart.download('gom.png')

It produces this URL:
http://chart.apis.google.com/chart?cht=gom&chs=440×220&chd=s:x&chl=Awesome

And the image:

Well, have fun. Please write a ticket for any bugs, patches or feature requests you have.

IPython is great for typing up quick tests. Unfortunately it is annoying when you have to import modules just to use it for one or two commands. autoimp is a Python module where it automatically imports modules when you refer to them. It works well with IPython simply by adding “import_all autoimp” somewhere in your “~/.ipython/ipythonrc” file.

Just a quick update. I have recently made some Python releases.

• PyGoogleChart 0.1.0 - Initial release of a Python wrapper for the Google Chart API.
• Python Call Graph 0.4.1 - Speed improvements for the visual call graph Python library.

I find readability very important when reading data. It saves time and energy. To me, Python’s pprint module is not easy to read in a lot of cases so I made my own. This is how pprint looks like at the moment:

BetterPrint is based on a lot of the source code, which looks about 10 years old. It makes more sense to me to have braces aligned by column rather than jammed together inline. BetterPrint also introduces colour to increase readability even more. As you can see from the following screen shot:

BetterPrint is compatible with Python’s pprint module, so you can simply “import betterprint” aliased as pprint like so:

try:
    import betterprint as pprint
except ImportError:
    import pprint

If you have setuptools installed simply run “easy_install betterprint”, or visit the web page for more details and installation instructions.

After promising myself to do it after many months, I’ve finally written a Greasemonkey script to reformat JSON output to be easily readable by a human. I may do cool things like syntax highlighting and expandable branches in the future, if the need and/or time arises.

I’ve just released pycallgraph 0.4.0. It has several major new features including a command line interface and measuring accumulative time per function.

The 0.4.0 pycallgraph CLI supports function filtering, timing filtering, maximum stack level and a few more settings. For example, to do a simple call graph on “myfile.py”:

pycallgraph-dot.py myfile.py mygraph.png

Here’s an example that doesn’t include the class Foo and outputs to a SVG file format:

pycallgraph-dot.py –exclude=”*.Foo.*” –image-format=svg myfile.py myfile.svg

Turns out far easier than modifying your source code to create a call graph.

Here’s one of the graphs from the source code examples colours.py:

As you can see it has green and orange gradients. One end of the gradient is green because of the number of calls is high and the other is orange because the function calls are taking the longest. All that with a function that looks like this:

def orange_green(calls, total_time):
    """Make a higher total time have an orange colour and a higher number
    of calls have a green colour using RGB.
    """
    return '#%02X%02X%02X' % (
        0x30 + total_time * 0xc0,
        0x30 + calls * 0xc0 + total_time * 0x70,
        0x30,
    )

I hope it’s useful to you!

I’ve made a small quick reference guide to SQLAlchemy if anyone is interested. I’ll update it as often as I have to look up something in the official documentation.

For the lack of updates, here is an update:

• Just released pycallgraph 0.3.1 which fixes a few bugs.
• This week hopefully releasing a pre-alpha of c80 which is an AJAX IRC client.
• Development of VirtuShare, a transparent peer-to-peer networking service, is still in progress.

I have released pyraknet 0.1.4! For those who don’t know… it lets you easily apply multi-player networking to your python game pretty easily. Enjoy!

Within 24 hours of releasing version 0.1.0, I’ve released 0.2.0 of pycallgraph. It’s just so fun to play with Graphviz…

I have just released pycallgraph which can create call graphs for Python programs. Quite useful for working out how Python programs work and to see if you have any problems in your program flow.

I’ve been releasing new versions of pyraknet like a mad man. pyraknet 0.1.3 has been released with the major change being a new Windows binary for Python 2.5. Other things include documentation, tests and one new method.

I have released the multiplayer network library pyraknet 0.1.2 with a few more features. I’ll be updating it with some more features soon.

This is a Django bug specific to Windows and it took me half a day to figure out because I trusted the datetime module! Basically if you set your TIME_ZONE in the settings.py file like so:

TIME_ZONE = 'Australia/Sydney'


The datetime and time modules will always return the UTC date.

The strange thing is that if you use “python manage.py shell” you get the bug but if you just use “python” you don’t get the bug.

Correct time:

c:\project>python
Python 2.4.3 (#69, Mar 29 2006, 17:35:34) [MSC v.1310 32 bit (Intel)] on win32
Type “help”, “copyright”, “credits” or “license” for more information.
>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2006, 9, 28, 12, 11, 38, 109000)


Django time:

c:\project>python manage.py shell --plain
Python 2.4.3 (#69, Mar 29 2006, 17:35:34) [MSC v.1310 32 bit (Intel)] on win32
Type “help”, “copyright”, “credits” or “license” for more information.
(InteractiveConsole)
>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2006, 9, 28, 3, 12, 16, 468000)


Possible solutions:

• Make wrapper functions/methods for datetime.datetime.now() and time.time(). This can break things if you’re not careful.
• Run django on a UNIX operating system
• Virtually run Django on a UNIX using a free VMware with a Virtual Appliance that has Django and many Python modules and more…
• Fix the bug