tomaster: Topological Mode Analysis on Steroids

tomaster implements algorithms for topological mode analysis.

The code is simple to read because it is written in pure Python.

The performance is good thanks to jit compilation with numba.

Usage

>>> from tomaster import tomato
>>> from sklearn import datasets
>>> X, y = datasets.make_moons(n_samples=1000, noise=0.05, random_state=1337)
>>> clusters, _ = tomato(X, k=5, n_clusters=2)

>>> import matplotlib.pyplot as plt
>>> plt.scatter(*X.T, c=clusters)
>>> plt.show()

Installation

pip install tomaster

Testing

pytest

API

def tomato(
    points,
    *,
    k,
    tau=None,
    n_clusters=None,
    relative_tau: bool = True,
    keep_cluster_labels: bool = False,
):
    """ToMATo clustering

    Parameters
    ----------

    points : np.ndarray
        Array of shape (n, dim)
    k : int
        Number of nearest neighbors to build the graph with
    tau : float or None
        Prominence threshold. Must not be specified if `n_clusters` is given.
    relative_tau : bool
        If `relative_tau` is set to `True`, `tau` will be multiplied by the standard deviation of the densities, making easier to have a unique value of `tau` for multiple datasets.       
    n_clusters : int or None
        Target number of clusters. Must not be specified if `tau` is given.
    keep_cluster_labels : bool
        If False, converts the labels to make them contiguous and start from 0.

    Returns
    -------

    clusters : np.ndarray
        Array of shape (n,) containing the cluster indexes.
    tau : float
        Prominence threshold. Only present if `n_clusters` was given.

    """

def tomato_img(
    img: np.ndarray, *, spatial_weight: float = 0, lab_space: bool = True, **kwargs
):
    """ToMATo for images

    Parameters
    ----------

    img : np.ndarray
        Image of shape (h, w) or (h, w, 3)
    spatial_weight : float
        Importance of the pixel positions in the distance function
    lab_space : bool
        If True, converts color images to the CIE L*a*b color space (<https://en.wikipedia.org/wiki/CIELAB_color_space>)

    see tomato() for other arguments.

    Returns
    -------

    clusters : np.ndarray
        Array of shape (h, w) containing the cluster indexes.
    """

References

• Chazal, Frédéric, Leonidas J. Guibas, Steve Y. Oudot, and Primoz Skraba. "Persistence-based clustering in riemannian manifolds." Journal of the ACM (JACM) 60, no. 6 (2013): 41. [pdf]

• Reference implementations: https://geometrica.saclay.inria.fr/data/ToMATo/, https://geometrica.saclay.inria.fr/data/Steve.Oudot/clustering/