A Python package to compute the smallest bounding ball of a point cloud in arbitrary dimensions. A Python/Cython binding of the popular miniball utility by Bernd Gärtner.
To my knowledge, this is currently the fastest implementation available in Python. For other implementations see:
miniballcppPython binding of the same C++ source (miniball)miniballPure Python implementation (slow)
The package is available via pip.
python -m pip install cyminiballimport cyminiball as miniball
import numpy as np
d = 2 # Number of dimensions
n = 10000 # Number of points
dt = np.float64 # Data type
points = np.random.randn(n, d)
points = points.astype(dt)
C, r2 = miniball.compute(points)
print("Center:", C)
print("Radius:", np.sqrt(r2))Additional output can be generated using the details flag and compute_max_chord().
C, r2, info = miniball.compute(points, details=True)
# Returns an info dict with the following keys:
# center: center
# radius: radius
# support: indices of the support points
# relative_error: error measure realtive to r2
# is_valid: numerical validity
# elapsed: time required
#
# The maximal chord is the longest line connecting any
# two of the support points. The following extends the
# info dict by the following keys:
# pts_max: point coordinates of the two points
# ids_max: ids of the two extreme points
# d_max: length of the maximal chord
(p1, p2), d_max = miniball.compute_max_chord(points, info=info)See examples/examples.py for further usage examples
Building the package requires
- Python 3.x
- Cython
- numpy
First, download the project and set up the environment.
git clone "https://github.com/hirsch-lab/cyminiball.git"
cd cyminiball
python -m pip install -r "requirements.txt"Then build and install the package. Run the tests/examples to verify the package.
./build_install.sh
python "tests/test_all.py"
python "examples/examples.py"For a comparison with miniballcpp, run the below command. In my experiments, the Cython-optimized code ran 10-50 times faster, depending on the number of points and point dimensions.
python "examples/comparison.py"
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