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7.1.6. nilearn.connectome.vec_to_sym_matrix

nilearn.connectome.vec_to_sym_matrix(vec, diagonal=None)

Return the symmetric matrix given its flattened lower triangular part.

Acts on the last dimension of the array if not 1-dimensional. Diagonal can be encompassed in vec or given separately. In both cases, note that diagonal elements are multiplied by sqrt(2).

New in version 0.3.


vec : numpy.ndarray or list of numpy arrays, shape (..., n_columns * (n_columns + 1) /2) or

(..., (n_columns - 1) * n_columns / 2) if diagonal is given seperately. The input array.

diagonal : numpy.ndarray, shape (..., n_columns), optional

The diagonal array to be stacked to vec. If None, the diagonal is assumed to be included in vec.


sym : numpy.ndarray, shape (..., n_columns, n_columns).

The output symmetric matrix.