How to find the Centre of a Polygon in Python

Finding the centre of of a polygon can be useful for many geomtrical analysis and processing techniques. This quick guide shows you how to find the centre of a polygon in python.

The Centroid

The centre of a polygon is also known as its centroid. It the arithmetic mean position of all the points that make up the polygon.

How to find the centre of a polygon in python

My preferred package for geometry analysis and processing in python is Shapely which happily for us, has a built-in method for finding the centroid of an object. We can just use:

mypolygon.centroid

This returns a shapely POINT object. This is all well and good, but in most situations we will want to process this further. So we can do a couple of further things to this centroid. Firstly we can output it in a more readable way:

mypolygon.centroid.wkt

(‘wkt’ stands for well known text), which outputs:

'POINT (3.351351351351351 1.897597597597598)'

Alternatively we can output the centroid as a pair of coordinates:

mypolygon.centroid.coords

(‘wkt’ stands for well known text), which outputs a python list.

[(3.351351351351351, 1.8975975975975976)]

Which is much more manageable.