Tuesday 10 March 2015

Python for Scientists

This year, 2014/2015, we started a new MSc course: Statistics for Computational Biology. We can see that there's a huge demand for bioinformaticians, for statisticians who can read biology, and for programmers who know about statistics and can apply stats to biological problems. So this new MSc encompasses programming, statistics and loads of the current hot topics in biology. It's the kind of MSc I would have loved to have done when I was younger.

As part of this degree, I'm teaching a brand new module called Programming for Scientists, which uses the Python programming language. This is aimed at students who have no prior programming knowledge, but have some science background. And in one semester we teach them the following:
  • The basics of programming: variables, loops, conditionals, functions
  • File handling (including CSV)
  • Plotting graphs using matplotlib
  • Exceptions
  • Version control using Git/Github
  • SQL database (basic design, queries, and using from SQLite from Python)
  • XML processing
  • Accessing data from online APIs 
We taught it as a hands-on module, lectures held in a room full of computers, programming as we go through the slides, with exercises interspersed and demonstrators on hand to help.

We had students sign up for this module from a surprisingly diverse set of backgrounds, from biology, from maths, from geography and even from international politics. We also had a large number of staff and PhD students from our Biology department (IBERS) who wanted to sit in on the module. This was a wonderful group of students to teach. They're people who wanted to learn, and mostly just seemed to absorb ideas that first year undergraduates struggle with. They raised their game to the challenge. 

Python's a great language for getting things done. So it makes a good hands-on language. However, it did highlight many of Python's limitations as a first teaching language. The objects/functions issue: I chose not to introduce the idea of objects at all. It's hard enough getting this much material comfortably into the time we had, and objects, classes and subclasses was something that I chose to leave out. So we have two ways to call functions: len(somelist) and somelist.reverse(). That's unfortunate. Variable scoping caught me out on occasion, and I'll have to fix that for next year. The Python 2 vs Python 3 issue was also annoying to work around. Hopefully next year we can just move to Python 3.

What impressed me most was the quality of the final assignment work. We asked the students to analyse a large amount of data about house sales, taken from http://data.gov.uk/ and population counts for counties in England and Wales taken from the Guardian/ONS. They had to access the data as XML over a REST-ful API, and it would take them approximately 4 days to download all the data they'd need. We didn't tell them in advance how large the data was and how slow it would be to pull it from an API. Undergrads would have complained. These postgrads just got on with it and recognised that the real world will be like this. If your data is large and slow to acquire then you'll need to test on a small subset, check and log any errors and start the assignment early. The students produced some clean, structured and well commented code and many creative summary graphs showing off their data processing and data visualisation skills.

I hope they're having just as much fun on their other modules for this course. I'm really looking forward to running this one again next year.

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