#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on July 10, 2019
@author: Nathan de Lara <nathan.delara@polytechnique.org>
@author: Thomas Bonald <bonald@enst.fr>
"""
from typing import Optional
import numpy as np
from scipy import sparse
from sknetwork.utils.membership import get_membership
[docs]def reindex_labels(labels: np.ndarray) -> np.ndarray:
"""Reindex clusters in decreasing order of size.
Parameters
----------
labels :
Label of each node.
Returns
-------
new_labels : np.ndarray
New label of each node.
Example
-------
>>> from sknetwork.clustering import reindex_labels
>>> labels = np.array([0, 1, 1])
>>> reindex_labels(labels)
array([1, 0, 0])
"""
_, index, counts = np.unique(labels, return_inverse=True, return_counts=True)
_, new_index = np.unique(np.argsort(-counts), return_index=True)
return new_index[index]
[docs]def aggregate_graph(input_matrix: sparse.csr_matrix, labels: Optional[np.ndarray] = None,
labels_row: Optional[np.ndarray] = None, labels_col: Optional[np.ndarray] = None) \
-> sparse.csr_matrix:
"""Aggregate graph per label. All nodes with the same label become a single node.
Negative labels are ignored (corresponding nodes are discarded).
Parameters
----------
input_matrix: sparse matrix
Adjacency or biadjacency matrix of the graph.
labels: np.ndarray
Labels of nodes.
labels_row: np.ndarray
Labels of rows (for bipartite graphs). Alias for labels.
labels_col: np.ndarray
Labels of columns (for bipartite graphs).
"""
if labels_row is not None:
membership_row = get_membership(labels_row)
else:
membership_row = get_membership(labels)
if labels_col is not None:
membership_col = get_membership(labels_col)
else:
membership_col = membership_row
aggregate_matrix = membership_row.T.dot(input_matrix).dot(membership_col)
return aggregate_matrix.tocsr()