group_columns(A, order=0)

Two columns are in the same group if in each row at least one of them has zero. A greedy sequential algorithm is used to construct groups.

Parameters

A : array_like or sparse matrix, shape (m, n)

Matrix of which to group columns.

order : int, iterable of int with shape (n,) or None

Permutation array which defines the order of columns enumeration. If int or None, a random permutation is used with :None:None:`order` used as a random seed. Default is 0, that is use a random permutation but guarantee repeatability.

Returns

groups : ndarray of int, shape (n,)

Contains values from 0 to n_groups-1, where n_groups is the number of found groups. Each value groups[i] is an index of a group to which ith column assigned. The procedure was helpful only if n_groups is significantly less than n.

Group columns of a 2-D matrix for sparse finite differencing .

Examples

See :

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GitHub : /scipy/optimize/_numdiff.py#214
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