Exemple #1
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def cvxopt_solver(G, h, A, b, c, n):
    # cvxopt doesn't allow redundant constraints in the linear program Ax = b,
    # so we need to do some preprocessing to find and remove any linearly
    # dependent rows in the augmented matrix [A | b].
    #
    # First we do Gaussian elimination to put the augmented matrix into row
    # echelon (reduced row echelon form is not necessary). Since b comes as a
    # numpy array (that is, a row vector), we need to convert it to a numpy
    # matrix before transposing it (that is, to a column vector).
    b = np.mat(b).T
    A_b = np.hstack((A, b))
    A_b, permutation = to_row_echelon(np.hstack((A, b)))
    # Next, we apply the inverse of the permutation applied to compute the row
    # echelon form.
    P = dictionary_to_permutation(permutation)
    A_b = P.I * A_b
    # Trim any rows that are all zeros. The call to np.any returns an array of
    # Booleans that correspond to whether a row in A_b is all zeros. Indexing
    # A_b by an array of Booleans acts as a selector. We need to use np.asarray
    # in order for indexing to work, since it expects a row vector instead of a
    # column vector.
    A_b = A_b[np.any(np.asarray(A_b) != 0, axis=1)]
    # Split the augmented matrix back into a matrix and a vector.
    A, b = A_b[:, :-1], A_b[:, -1]
    # Apply the linear programming solver; cvxopt requires that these are all
    # of a special type of cvx-specific matrix.
    G, h, A, b, c = (cvx_matrix(M) for M in (G, h, A, b, c))
    solution = cvx_solvers.lp(c, G, h, A, b)
    if solution['status'] == 'optimal':
        return True, solution['x']
    # TODO status could be 'unknown' here, but we're currently ignoring that
    return False, None
Exemple #2
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def cvxopt_solver(G, h, A, b, c, n):
    # cvxopt doesn't allow redundant constraints in the linear program Ax = b,
    # so we need to do some preprocessing to find and remove any linearly
    # dependent rows in the augmented matrix [A | b].
    #
    # First we do Gaussian elimination to put the augmented matrix into row
    # echelon (reduced row echelon form is not necessary). Since b comes as a
    # numpy array (that is, a row vector), we need to convert it to a numpy
    # matrix before transposing it (that is, to a column vector).
    b = np.mat(b).T
    A_b = np.hstack((A, b))
    A_b, permutation = to_row_echelon(np.hstack((A, b)))
    # Next, we apply the inverse of the permutation applied to compute the row
    # echelon form.
    P = dictionary_to_permutation(permutation)
    A_b = P.I * A_b
    # Trim any rows that are all zeros. The call to np.any returns an array of
    # Booleans that correspond to whether a row in A_b is all zeros. Indexing
    # A_b by an array of Booleans acts as a selector. We need to use np.asarray
    # in order for indexing to work, since it expects a row vector instead of a
    # column vector.
    A_b = A_b[np.any(np.asarray(A_b) != 0, axis=1)]
    # Split the augmented matrix back into a matrix and a vector.
    A, b = A_b[:, :-1], A_b[:, -1]
    # Apply the linear programming solver; cvxopt requires that these are all
    # of a special type of cvx-specific matrix.
    G, h, A, b, c = (cvx_matrix(M) for M in (G, h, A, b, c))
    solution = cvx_solvers.lp(c, G, h, A, b)
    if solution['status'] == 'optimal':
        return True, solution['x']
    # TODO status could be 'unknown' here, but we're currently ignoring that
    return False, None
Exemple #3
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def test_dictionary_to_permutation():
    permutation = {0: 1, 1: 2, 2: 0}
    expected = np.mat([[0, 1, 0], [0, 0, 1], [1, 0, 0]])
    actual = dictionary_to_permutation(permutation)
    assert np.all(expected == actual)
Exemple #4
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def test_dictionary_to_permutation():
    permutation = {0: 1, 1: 2, 2: 0}
    expected = np.mat([[0, 1, 0], [0, 0, 1], [1, 0, 0]])
    actual = dictionary_to_permutation(permutation)
    assert np.all(expected == actual)