Faster Image Transforms With Cython

This is the second post on how to accelerate Python with Cython. The previous post used Cython to declare static C data types in Python, to speed up the runtime of a prime number generator. In this post we shall be modifying a more complex program, one that performs an image transform on a map. This will allow me to demonstrate some more advanced Cython techniques, such as importing C functions from the C math library, using memory views of Numpy arrays and turning off the Python global interpreter lock (GIL).

As with the previous post, we shall be making a series of Cython modifications to Python code, noting the speed improvement with each step. As we go, we’ll be using the Cython compiler’s annotation feature to see which lines are converted into C at each stage, and which lines are still using Python objects and functions. And as we tune the code to run at increasingly higher speeds, we shall be profiling it to see what’s still holding us up, and where to refocus our attention.

Although I will be using Python 3 on a Mac, the instructions I give will mostly be platform agnostic:  I will assume you have installed Cython on your system (on Windows, Linux or OS/X) and have followed and understood the installation and testing steps in my previous post. This will be essential if you are to follow the steps I outline below. As stated in the previous post, Cython is not for Python beginners.

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From Python To Cython

This longer post will show you some of the coding skills you’ll need for turning your existing Python code into the Python-C hybrid we call Cython. In doing so, we’ll be digging into some C static data types, to see how much faster Python code will run, and restructuring some Python code along the way for maximum speed.

With Cython, all the benefits of Python are still yours – easily readable code, fast development cycles, powerful high level commands, maintainability, a suite of web development frameworks, a huge standard library for data science, machine learning, imaging, databases and security, plus easy manipulation of files, documents and strings. You should still use Python for all these things – these are what Python does best. But you should also consider combining them with Cython to speed up the computationally intensive Python functions that needs to be fast. Continue reading “From Python To Cython”

The Toolkit – Updated

Alas, dear Windows, it was not to be. I’m afraid I’ve been seeing other platforms. Specifically, I’ve been spending time with OS/X behind your back.  It was just too painful to be with you.  All those arguments, the shouting, the hair-pulling, the throwing things across the room.

Sure, you’re a lot less volatile than you used to be. And you don’t do the tearful breakdown thing any more. Yes, I know I can do almost anything with you that I can with OS/X, but everything just takes longer. OK, you want me to be honest? Fine. I find you excruciatingly frustrating to be with.  Why is it always ME navigating around YOUR moods? I mean, why is it that after 25 years, everything with you is STILL a workaround?

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Using AppleScript To Launch Python

OK, one for the Mac users. Continuing the  theme of user interfaces, here’s a simple but powerful way of using AppleScript to create a user interface for your Python programs and shell scripts and sending the results to just about any application installed on your Mac.

This solution has the advantage over Python’s native Tkinter in that the development time is much faster, and uses the speech synthesis features of OS/X to make your code much easier to use for the non-technical, elderly or visually impaired.

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