The programming language doesn't matter; measuring the runtime complexity of an algorithm works the same way regardless of the language. Analysis of Algorithms by Stanford on Google Code University is a very good resource for teaching yourself how to analyze the runtime complexity of algorithms and code.
If all you want to do is measure the elapsed time that a function or section of code took to run in Python, then you can use the timeit or time modules, depending on how long the code needs to run.
