kayarre / miniball

Efficient computation of the smallest bounding ball of a point set, in arbitrary number of dimensions

miniball

A Python module to efficiently compute the smallest bounding ball of a point set, in arbitrary number of dimensions.

The algorithm runs in approximatively linear time in respects to the number of input points. This is NOT a derivative nor a port of Bernd Gaertner's C++ library.

This project is licensed under the MIT License

Requirements

miniball 1.0 requires

• Python 2.7, >=3.4
• Numpy

Installation

$ pip install miniball

Usage

Here is how you can get the smallest bounding ball of a set of points

>>> import numpy
>>> import miniball
>>> S = numpy.random.randn(100, 2)
>>> C, r2 = miniball.get_bounding_ball(S)

The center of the bounding ball is C, its radius is the square root of r2. And that's it ! miniball does only one thing with one function.

Implementation notes

The algorithm implemented is Welzl's algorithm. It is a pure Python implementation, it is not a binding of the popular C++ package Bernd Gaertner's miniball.

The algorithm, although often presented in its recursive form, is here implemented in an iterative fashion. Python have an hard-coded recursion limit, therefore a recursive implementation of Welzl's algorithm would have an artificially limited number of point it could process.