Mean shift clustering using a flat kernel.
Mean shift clustering aims to discover "blobs" in a smooth density of samples. It is a centroid-based algorithm, which works by updating candidates for centroids to be the mean of the points within a given region. These candidates are then filtered in a post-processing stage to eliminate near-duplicates to form the final set of centroids.
Seeding is performed using a binning technique for scalability.
Read more in the :ref:`User Guide <mean_shift>`.
Parameters ---------- bandwidth : float, optional Bandwidth used in the RBF kernel.
If not given, the bandwidth is estimated using sklearn.cluster.estimate_bandwidth; see the documentation for that function for hints on scalability (see also the Notes, below).
seeds : array, shape=n_samples, n_features
, optional Seeds used to initialize kernels. If not set, the seeds are calculated by clustering.get_bin_seeds with bandwidth as the grid size and default values for other parameters.
bin_seeding : boolean, optional If true, initial kernel locations are not locations of all points, but rather the location of the discretized version of points, where points are binned onto a grid whose coarseness corresponds to the bandwidth. Setting this option to True will speed up the algorithm because fewer seeds will be initialized. default value: False Ignored if seeds argument is not None.
min_bin_freq : int, optional To speed up the algorithm, accept only those bins with at least min_bin_freq points as seeds. If not defined, set to 1.
cluster_all : boolean, default True If true, then all points are clustered, even those orphans that are not within any kernel. Orphans are assigned to the nearest kernel. If false, then orphans are given cluster label -1.
n_jobs : int or None, optional (default=None) The number of jobs to use for the computation. This works by computing each of the n_init runs in parallel.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context. ``-1`` means using all processors. See :term:`Glossary <n_jobs>` for more details.
max_iter : int, default=300 Maximum number of iterations, per seed point before the clustering operation terminates (for that seed point), if has not converged yet.
.. versionadded:: 0.22
Attributes ---------- cluster_centers_ : array, n_clusters, n_features
Coordinates of cluster centers.
labels_ : Labels of each point.
n_iter_ : int Maximum number of iterations performed on each seed.
.. versionadded:: 0.22
Examples -------- >>> from sklearn.cluster import MeanShift >>> import numpy as np >>> X = np.array([1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]
) >>> clustering = MeanShift(bandwidth=2).fit(X) >>> clustering.labels_ array(1, 1, 1, 0, 0, 0
) >>> clustering.predict([0, 0], [5, 5]
) array(1, 0
) >>> clustering MeanShift(bandwidth=2)
Notes -----
Scalability:
Because this implementation uses a flat kernel and a Ball Tree to look up members of each kernel, the complexity will tend towards O(T*n*log(n)) in lower dimensions, with n the number of samples and T the number of points. In higher dimensions the complexity will tend towards O(T*n^2).
Scalability can be boosted by using fewer seeds, for example by using a higher value of min_bin_freq in the get_bin_seeds function.
Note that the estimate_bandwidth function is much less scalable than the mean shift algorithm and will be the bottleneck if it is used.
References ----------
Dorin Comaniciu and Peter Meer, "Mean Shift: A robust approach toward feature space analysis". IEEE Transactions on Pattern Analysis and Machine Intelligence. 2002. pp. 603-619.