fugu Sa-Me Japanese Vegan & Rubber Eco-Friendly Sa-Me Mid-Calf Boots with with Rubber Sole Gray 406708f - bewegungswerkstatt.website Basic Introduction to Cython Edmund Martin Leave a comment

Python is often criticized for being slow. In many cases pure Python is fast enough, there are certain cases where Python may not give you the performance you need. In recent years a fair number of Python programmers have made the jump to Golang for performance reasons. However there are a number of ways you can improve the performance of your Python code such as using PyPy, writing C extensions or trying your hand at Cython.

What is Cython?

Cython is a superset of the Python language. This means that the vast majority of Python code, is also valid Cython code. Cython allows users to write Cython modules which are then compile and can be used within in Python code. This means that users can port performance critical code into Cython and instantly see increases in performance. The great thing about Cython code is that you can determine how much to optimize your code.  Simply copying and compiling your Python code might see you make performance gains of 8-12%, whereas more serious optimization of your code can lead to significantly better performance.

Installing Cython

Installing Cython on Linux is very easy to do and just requires you to use the ‘pip install cython’ command. Those on Windows devices will likely have a much tougher time, with the simplest solution seeming to be just installing ‘Visual Code Community’ and selecting both the C++ and Python support options. You can then just install Cython like you would any other Python package.

Using Pure Python

We are going to begin with compiling a pure Python function. This is a very simple task, and can achieve some limited performance benefits, with a more noted increase in performance for functions which make use of for and while loops. To begin we simply save the below code into a file called ‘looping.pyx’.

def multiply_elements_by_index(number_list):
    output = 0
    for i in range(len(number_list)):
        output += number_list[i] * i
    return output

This very simple function takes a list of numbers and then multiples each number by it’s index, and returning the sum of the results. This code is both valid Python and Cython code. However, it takes no advantage of any Cython optimizations other than the compilation of the code into C.

We run the below command to create Cython module which can be used in Python: