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First steps

The purpose of this guide is to illustrate the possible uses of geomstats.

INSTALL GEOMSTATS WITH PIP3

From a terminal (OS X & Linux), you can install geomstats and its requirements with pip3 as follows:

pip3 install geomstats

This method installs the latest version of geomstats that is uploaded on PyPi.

INSTALL GEOMSTATS FROM GITHUB

From a terminal (OS X & Linux), you can install geomstats and its requirements via Git as follows:

git clone https://github.com/geomstats/geomstats.git
pip3 install -r requirements.txt

This methods installs the `latest GitHub version<https://github.com/geomstats/geomstats>`_. Developers should install this version, together with the development requirements and the optional requirements to enable tensorflow and pytorch backends:

pip3 install -r dev-requirements.txt -r opt-requirements.txt

CHOOSE THE BACKEND

Geomstats can run seemlessly with numpy, tensorflow or pytorch. Note that pytorch and tensorflow requirements are optional, as geomstats can be used with numpy only. By default, the numpy backend is used. The visualizations are only available with this backend.

To get the tensorflow and pytorch versions compatible with geomstats, install the optional requirements:

pip3 install -r opt-requirements.txt

You can choose your backend by setting the environment variable GEOMSTATS_BACKEND to numpy, tensorflow or pytorch, and importing the backend module. From the command line:

export GEOMSTATS_BACKEND=pytorch

and in the Python3 code:

import geomstats.backend as gs

FIRST EXAMPLES

To use geomstats for learning algorithms on Riemannian manifolds, you need to follow three steps: - instantiate the manifold of interest, - instantiate the learning algorithm of interest, - run the algorithm. The data should be represented by the structure gs.array, which represents numpy arrays, tensorflow or pytorch tensors, depending on the choice of backend.

As an example, the following code snippet illustrates the use of K-means on simulated data on the 5-dimensional hypersphere.

from geomstats.geometry.hypersphere import Hypersphere
from geomstats.learning.online_kmeans import OnlineKMeans

sphere = Hypersphere(dimension=5)

data = sphere.random_uniform(n_samples=10)

clustering = OnlineKMeans(metric=sphere.metric, n_clusters=4)
clustering = clustering.fit(data)

The following code snippet shows the use of tangent Principal Component Analysis on simulated data on the space of 3D rotations.

from geomstats.geometry.special_orthogonal import SpecialOrthogonal
from geomstats.learning.pca import TangentPCA

so3 = SpecialOrthogonal(n=3)
metric = so3.bi_invariant_metric

data = so3.random_uniform(n_samples=10)

tpca = TangentPCA(metric=metric, n_components=2)
tpca = tpca.fit(data)
tangent_projected_data = tpca.transform(data)

All geometric computations are performed behind the scenes. The user only needs a high-level understanding of Riemannian geometry. Each algorithm can be used with any of the manifolds and metric implemented in the package.

To see additional examples, visit the page :ref:`examples`.