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nilearn.connectome.sym_matrix_to_vec(symmetric, discard_diagonal=False)[source]

Return the flattened lower triangular part of an array.

If diagonal is kept, diagonal elements are divided by sqrt(2) to conserve the norm.

Acts on the last two dimensions of the array if not 2-dimensional.

Added in version 0.3.

symmetricnumpy.ndarray or list of numpy arrays, shape (…, n_features, n_features)

Input array.

discard_diagonalboolean, default=False

If True, the values of the diagonal are not returned.


The output flattened lower triangular part of symmetric. Shape is (…, n_features * (n_features + 1) / 2) if discard_diagonal is False and (…, (n_features - 1) * n_features / 2) otherwise.