genieclust Package for R and Python

Genie: Fast and Robust Hierarchical Clustering

Genie finds meaningful clusters. It does so quickly, even in large datasets.

A comprehensive tutorial, benchmarks, and a reference manual is available at https://genieclust.gagolewski.com/.

When using genieclust in research publications, please cite (Gagolewski, 2021) and (Gagolewski, Bartoszuk, Cena, 2016) as specified below. Thank you.

About

Genie is a robust hierarchical clustering algorithm (see Gagolewski, Bartoszuk, Cena, 2016). Its original implementation was included in the R package genie. This is its faster and more capable variant.

The idea behind Genie is beautifully simple. First, make each individual point the only member of its own cluster. Then, keep merging pairs of the closest clusters, one after another. However, to prevent the formation of clusters of highly imbalanced sizes, a point group of the smallest size is sometimes combined with its nearest counterpart.

Genie's appealing simplicity goes hand in hand with its usability. It often outperforms other clustering approaches such as K-means, BIRCH, or average, complete, and Ward's linkage on benchmark data. Of course, there is no, nor will there ever be, a single best universal clustering approach for every kind of problem, but Genie is definitely worth a try.

As with all distance-based methods (this includes k-means and DBSCAN as well), applying data preprocessing and feature engineering techniques (e.g., feature scaling, feature selection, dimensionality reduction) might lead to more meaningful results.

Genie is based on Euclidean minimal spanning trees. Thus, it can also be pretty fast: thanks to quitefastmst, determining the entire cluster hierarchy for datasets containing millions of points can be completed in minutes. Therefore, it is well suited to solving extreme clustering tasks (involving large datasets with a high number of clusters to detect).

genieclust also allows clustering with respect to mutual reachability distances, enabling it to act as an alternative to HDBSCAN* (Campello et al., 2013) that can identify any number of clusters or their entire hierarchy. Notably, it doesn't depend on DBSCAN's somewhat difficult to set eps parameter.

When combined with the deadwood package, it can act as an outlier detector.

Other Package Features

The package also features an implementation of:

• inequality measures (the Gini, Bonferroni, or de Vergottini index),

• external cluster validity measures (e.g., the normalised clustering accuracy and partition similarity indices such as the adjusted Rand, Fowlkes-Mallows, or mutual information scores),

• internal cluster validity indices (e.g., the Calinski-Harabasz, Davies-Bouldin, Ball-Hall, Silhouette, or generalised Dunn indices).

Author and Contributors

Author and Maintainer: Marek Gagolewski

Contributors: Maciej Bartoszuk, Anna Cena (R packages genie and CVI), and Peter M. Larsen (rectangular_lsap).

Examples, Tutorials, and Documentation

The R interface is compatible with stats::hclust():

X <- ...  # some data
h <- gclust(X)  # dist(X) also works, but is slower
plot(h)  # plot cluster dendrogram
cutree(h, k=2)
# or simply:  genie(X, k=2)  (faster)

To learn more about R, check out Marek's open-access textbook Deep R Programming.

The Python language version of genieclust has a scikit-learn-like API:

import genieclust
X = ...  # some data
g = genieclust.Genie(n_clusters=2)
labels = g.fit_predict(X)

Tutorials and the package documentation are available here.

To learn more about Python, check out Marek's open-access textbook Minimalist Data Wrangling in Python.

How to Install

Python Version

To install from PyPI, call:

pip3 install genieclust  # python3 -m pip install genieclust

The package requires Python 3.9+ with cython, numpy, scikit-learn, quitefastmst. and deadwood.

R Version

To install from CRAN, call:

install.packages("genieclust")

Other

The core functionality is implemented in the form of a header-only C++ library. It can thus be easily adapted for use in other projects.

New contributions are welcome, e.g., Julia, Matlab/GNU Octave wrappers.

License

Copyright (C) 2018–2026 Marek Gagolewski https://www.gagolewski.com/

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License Version 3, 19 November 2007, published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License Version 3 for more details. You should have received a copy of the License along with this program. If not, see (https://www.gnu.org/licenses/).

The file src/c_scipy_rectangular_lsap.h is adapted from the scipy project (https://scipy.org/scipylib), source: /scipy/optimize/rectangular_lsap/rectangular_lsap.cpp. Author: Peter M. Larsen. Distributed under the BSD-3-Clause license.

The implementation of internal cluster validity measures were adapted from our previous project (Gagolewski, Bartoszuk, Cena, 2021); see optim_cvi. Originally distributed under the GNU Affero General Public License Version 3.

References

Gagolewski, M., genieclust: Fast and robust hierarchical clustering, SoftwareX 15, 2021, 100722. DOI: 10.1016/j.softx.2021.100722. https://genieclust.gagolewski.com/.

Gagolewski, M., Bartoszuk, M., Cena, A., Genie: A new, fast, and outlier-resistant hierarchical clustering algorithm, Information Sciences 363, 2016, 8–23. DOI: 10.1016/j.ins.2016.05.003.

Gagolewski, M., Bartoszuk, M., Cena, A., Are cluster validity measures (in)valid?, Information Sciences 581, 2021, 620–636. DOI: 10.1016/j.ins.2021.10.004.

Gagolewski, M., Cena, A., Bartoszuk, M., Brzozowski, L., Clustering with minimum spanning trees: How good can it be?, Journal of Classification 42, 2025, 90–112. DOI: 10.1007/s00357-024-09483-1.

Gagolewski, M., Normalised clustering accuracy: An asymmetric external cluster validity measure, Journal of Classification 42, 2025, 2–30. DOI: 10.1007/s00357-024-09482-2.

Gagolewski, M., A framework for benchmarking clustering algorithms, SoftwareX 20, 2022, 101270. DOI: 10.1016/j.softx.2022.101270. https://clustering-benchmarks.gagolewski.com/.

Campello, R.J.G.B., Moulavi, D., Sander, J., Density-based clustering based on hierarchical density estimates, Lecture Notes in Computer Science 7819, 2013, 160–172. DOI: 10.1007/978-3-642-37456-2_14.

Mueller, A., Nowozin, S., Lampert, C.H., Information theoretic clustering using minimum spanning trees, DAGM-OAGM, 2012.

See genieclust's homepage for more references.