Archive for September, 2009

Importing a normal, rectangular map of Middle-earth as a Google Earth overlay is too narrow toward the north.

I wanted to measure distances in Tolkien's Middle-earth. While a flat map distorts such measurements, it occured to me that Google Earth can correctly measure both lines and paths across the curved surface of the globe. I soon found excellent documentation for using image overlays with Google Earth, so I downloaded a map of Middle-earth and tried placing it on the globe.

Imagine my disappointment when I saw the result shown in the above image! At first I made the mistake of not holding down the Shift key when resizing the image in Google Earth; the Shift key is absolutely critical for the image to maintain its aspect ratio as you stretch it to the right dimensions. But even after learning this habit, it was painfully clear that the Middle-earth map's projection was different from that expected by Google Earth: the map is far too narrow at the top.

Obviously, it was time to pull out Python, my favorite programming language, and see whether the Python Imaging Library could help me make short work of converting a map from one projection to another.

My Python table at the Atlanta Linux Fest. You can also watch a short video of me demonstrating a depth-first search to some students who dropped by the table. (Thanks, Richard Davies, for the video!)

Running the Python table at the Atlanta Linux Fest this past weekend was a really incredible experience.

First, there was the great feeling that the pillars of the Python community were standing behind me as I stepped forward to represent my favorite programming language. It was Andrew Kuchling who noticed that exhibitor tables at the Fest were free for non-profits like the Python Software Foundation, and Steve Holden who forwarded me a heads-up since I live in Atlanta (the Fest had not yet made it on to my radar). The inimitable Aahz personally shipped me the promotional kit, including a huge “Python” banner and stacks of brochures, that he himself had just used at OSCON 2009. And, completing the loop, it was Andrew who followed up to ask if there were any last things that I needed, and sent me a pile of over one hundred Python stickers that wound up being very popular at the Fest. (I returned home with exactly one, which is sitting next to me on my desk as I type this!)

Here are some lessons that I learned from the experience:

I would like some advice from Zope and Plone folks about how to create forms that are not only easy for other developers to specialize, but which allow several specializations to be composed together. While I have used zope.formlib and z3c.form before for simple tasks, I have not yet been able to tell whether they support these more advanced kinds of operations.

Some background: I am doing some work on GetPaid for Plone with the generous funding of Derek Richardson who, if his dreams had not carried him away from grad school at the end of the Spring semester, would have tackled this same work as part of the 2009 Google Summer of Code.

The current mechanisms that GetPaid provides for customizing its checkout process are very primitive, and my task is to improve them. That is why I have been thinking about customizing forms.

The August issue of Python Magazine is out, and the cover issue is one of the most exciting that I have had the privilege to publish. Following up on his popular talk at PyCon 2009, professor of computer science Dr. Bill Punch has written an article for us with his colleague Dr. Richard Enbody about replacing C++ with Python in Michigan State University's introductory programming class.

The difficulty they faced was that the second and subsequent classes in Michigan State's curriculum have continued using the C++ language; only the initial course could change to Python. While non-majors taking the introductory course get to learn Python and leave, the computer science majors have to then start the second course without any specific knowledge of C++. How much, skeptics wondered, would it hurt the Python students to be a full semester behind in their C++ knowledge compared to students who took the “old” C++ version of the introductory course?

The circumstances at Michigan State wound up being perfect for making the change to Python a full-fledged, statistically valid experiment to determine how much student grades would be hurt because of the switch. Read the article for the detailed results, but I can report — with great satisfaction — that the Python students proved themselves the equals of their C++ peers, and also that very exciting and unexpected results ensued among the students whom the study was not looking at: the non-majors, for which this was their only programming course, and the seasoned grad students, who rolled up their sleeves and learned Python in order to be able to TA the course. Again, see the article for all of the details!

What else do we have this month? Articles about how easy concurrency becomes with Stackless Python; about documenting your software projects using the powerful Sphinx documentation system; about creating simple graphs with the industry-strength matplotlib plotting library; a guide to the details of hashing algorithms, and how they relate to the Python dictionary implementation; and, finally, the usual thoughts and ponderings from both myself and from Steve Holden of the Python Software Foundation. Come join us!