Esempio n. 1
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    def test_psd_nsd_parameters(self):
        # Test valid rank-deficeint PSD parameter.
        np.random.seed(42)
        a = np.random.normal(size=(100, 95))
        a2 = a.dot(a.T)  # This must be a PSD matrix.
        p = Parameter((100, 100), PSD=True)
        p.value = a2
        self.assertItemsAlmostEqual(p.value, a2, places=10)

        # Test positive definite matrix with non-distinct eigenvalues
        m, n = 10, 5
        A = np.random.randn(
            m, n) + 1j * np.random.randn(m, n)  # a random complex matrix
        A = np.dot(A.T.conj(),
                   A)  # a random Hermitian positive definite matrix
        A = np.vstack([
            np.hstack([np.real(A), -np.imag(A)]),
            np.hstack([np.imag(A), np.real(A)])
        ])

        p = Parameter(shape=(2 * n, 2 * n), PSD=True)
        p.value = A
        self.assertItemsAlmostEqual(p.value, A)

        # Test invalid PSD parameter
        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), PSD=True, value=[[1, 0], [0, -1]])
        self.assertEqual(str(cm.exception),
                         "Parameter value must be positive semidefinite.")

        # Test invalid NSD parameter
        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), NSD=True, value=[[1, 0], [0, -1]])
        self.assertEqual(str(cm.exception),
                         "Parameter value must be negative semidefinite.")
Esempio n. 2
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    def test_parameter_expressions(self):
        """Test that expressions with parameters are updated properly.
        """
        x = Variable()
        y = Variable()
        x0 = Parameter()
        xSquared = x0*x0 + 2*x0*(x - x0)

        # initial guess for x
        x0.value = 2

        # make the constraint x**2 - y == 0
        g = xSquared - y

        # set up the problem
        obj = abs(x - 1)
        prob = Problem( Minimize( obj ), [ g == 0 ] )
        prob.solve()
        x0.value = 1
        prob.solve()
        self.assertAlmostEqual(g.value, 0)

        # Test multiplication.
        prob = Problem( Minimize( x0*x ), [ x == 1 ] )
        x0.value = 2
        prob.solve()
        x0.value = 1
        prob.solve()
        self.assertAlmostEqual(prob.value, 1)
Esempio n. 3
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    def test_parameters(self):
        p = Parameter(name='p')
        self.assertEqual(p.name(), "p")
        self.assertEqual(p.size, (1, 1))

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = 1
        self.assertEqual(str(cm.exception),
                         "Invalid dimensions (1,1) for Parameter value.")

        val = -np.ones((4, 3))
        val[0, 0] = 2

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception),
                         "Invalid sign for Parameter value.")

        p = Parameter(4, 3, sign="negative")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception),
                         "Invalid sign for Parameter value.")

        # No error for unknown sign.
        p = Parameter(4, 3)
        p.value = val
Esempio n. 4
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    def test_parameter(self):
        """Test the parameter class.
        """
        x = Parameter(2, complex=False)
        y = Parameter(2, complex=True)
        z = Parameter(2, imag=True)

        assert not x.is_complex()
        assert not x.is_imag()
        assert y.is_complex()
        assert not y.is_imag()
        assert z.is_complex()
        assert z.is_imag()

        with self.assertRaises(Exception) as cm:
            x.value = np.array([1j, 0.])
        self.assertEqual(str(cm.exception), "Parameter value must be real.")

        y.value = np.array([1., 0.])
        y.value = np.array([1j, 0.])

        with self.assertRaises(Exception) as cm:
            z.value = np.array([1., 0.])
        self.assertEqual(str(cm.exception),
                         "Parameter value must be imaginary.")
Esempio n. 5
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    def test_parameter_expressions(self):
        """Test that expressions with parameters are updated properly.
        """
        x = Variable()
        y = Variable()
        x0 = Parameter()
        xSquared = x0 * x0 + 2 * x0 * (x - x0)

        # initial guess for x
        x0.value = 2

        # make the constraint x**2 - y == 0
        g = xSquared - y

        # set up the problem
        obj = abs(x - 1)
        prob = Problem(Minimize(obj), [g == 0])
        prob.solve()
        x0.value = 1
        prob.solve()
        self.assertAlmostEqual(g.value, 0)

        # Test multiplication.
        prob = Problem(Minimize(x0 * x), [x == 1])
        x0.value = 2
        prob.solve()
        x0.value = 1
        prob.solve()
        self.assertAlmostEqual(prob.value, 1)
Esempio n. 6
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    def test_parameters_successes(self):
        # Parameter names and dimensions
        p = Parameter(name='p')
        self.assertEqual(p.name(), "p")
        self.assertEqual(p.shape, tuple())

        # Entry-wise constraints on parameter values.
        val = -np.ones((4, 3))
        val[0, 0] = 2
        p = Parameter((4, 3))
        p.value = val

        # Initialize a parameter with a value; later, set it to None.
        p = Parameter(value=10)
        self.assertEqual(p.value, 10)
        p.value = 10
        p.value = None
        self.assertEqual(p.value, None)

        # Test parameter representation.
        p = Parameter((4, 3), nonpos=True)
        self.assertEqual(repr(p), 'Parameter((4, 3), nonpos=True)')

        # Test valid diagonal parameter.
        p = Parameter((2, 2), diag=True)
        p.value = sp.csc_matrix(np.eye(2))
        self.assertItemsAlmostEqual(p.value.todense(), np.eye(2), places=10)
Esempio n. 7
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    def test_parameters(self):
        p = Parameter(name='p')
        self.assertEqual(p.name(), "p")
        self.assertEqual(p.size, (1,1))

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = 1
        self.assertEqual(str(cm.exception), "Invalid dimensions (1,1) for Parameter value.")

        val = -np.ones((4,3))
        val[0,0] = 2

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception), "Invalid sign for Parameter value.")

        p = Parameter(4, 3, sign="negative")
        with self.assertRaises(Exception) as cm:         
            p.value = val
        self.assertEqual(str(cm.exception), "Invalid sign for Parameter value.")

        # No error for unknown sign.
        p = Parameter(4, 3)
        p.value = val
Esempio n. 8
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    def test_div_expression(self):
        # Vectors
        exp = self.x/2
        self.assertEqual(exp.curvature, s.AFFINE)
        self.assertEqual(exp.sign, s.UNKNOWN)
        # self.assertEqual(exp.canonical_form[0].shape, (2, 1))
        # self.assertEqual(exp.canonical_form[1], [])
        # self.assertEqual(exp.name(), c.name() + " * " + self.x.name())
        self.assertEqual(exp.shape, (2,))

        with self.assertRaises(Exception) as cm:
            (self.x/[2, 2, 3])
        print(cm.exception)
        self.assertRegexpMatches(str(cm.exception),
                                 "Incompatible shapes for division.*")

        c = Constant([3.0, 4.0, 12.0])
        self.assertItemsAlmostEqual(
          (c / Constant([1.0, 2.0, 3.0])).value, np.array([3.0, 2.0, 4.0]))

        # Constant expressions.
        c = Constant(2)
        exp = c/(3 - 5)
        self.assertEqual(exp.curvature, s.CONSTANT)
        self.assertEqual(exp.shape, tuple())
        self.assertEqual(exp.sign, s.NONPOS)

        # Parameters.
        p = Parameter(nonneg=True)
        exp = 2/p
        p.value = 2
        self.assertEqual(exp.value, 1)

        rho = Parameter(nonneg=True)
        rho.value = 1

        self.assertEqual(rho.sign, s.NONNEG)
        self.assertEqual(Constant(2).sign, s.NONNEG)
        self.assertEqual((Constant(2)/Constant(2)).sign, s.NONNEG)
        self.assertEqual((Constant(2)*rho).sign, s.NONNEG)
        self.assertEqual((rho/2).sign, s.NONNEG)

        # Broadcasting.
        x = cp.Variable((3, 3))
        c = np.arange(1, 4)[:, None]
        expr = x / c
        self.assertEqual((3, 3), expr.shape)
        x.value = np.ones((3, 3))
        A = np.ones((3, 3)) / c
        self.assertItemsAlmostEqual(A, expr.value)

        with self.assertRaises(Exception) as cm:
            (x/c[:, 0])
        print(cm.exception)
        self.assertRegexpMatches(str(cm.exception),
                                 "Incompatible shapes for division.*")
Esempio n. 9
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    def test_parameters_failures(self):
        p = Parameter(name='p')
        self.assertEqual(p.name(), "p")
        self.assertEqual(p.shape, tuple())

        p = Parameter((4, 3), nonneg=True)
        with self.assertRaises(Exception) as cm:
            p.value = 1
        self.assertEqual(str(cm.exception), "Invalid dimensions () for Parameter value.")

        val = -np.ones((4, 3))
        val[0, 0] = 2

        p = Parameter((4, 3), nonneg=True)
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception), "Parameter value must be nonnegative.")

        p = Parameter((4, 3), nonpos=True)
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception), "Parameter value must be nonpositive.")

        with self.assertRaises(Exception) as cm:
            p = Parameter(2, 1, nonpos=True, value=[2, 1])
        self.assertEqual(str(cm.exception), "Parameter value must be nonpositive.")

        with self.assertRaises(Exception) as cm:
            p = Parameter((4, 3), nonneg=True, value=[1, 2])
        self.assertEqual(str(cm.exception), "Invalid dimensions (2,) for Parameter value.")

        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), diag=True, symmetric=True)
        self.assertEqual(str(cm.exception),
                         "Cannot set more than one special attribute in Parameter.")

        # Boolean
        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), boolean=True, value=[[1, 1], [1, -1]])
        self.assertEqual(str(cm.exception), "Parameter value must be boolean.")

        # Integer
        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), integer=True, value=[[1, 1.5], [1, -1]])
        self.assertEqual(str(cm.exception), "Parameter value must be integer.")

        # Diag.
        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), diag=True, value=[[1, 1], [1, -1]])
        self.assertEqual(str(cm.exception), "Parameter value must be diagonal.")

        # Symmetric.
        with self.assertRaises(Exception) as cm:
            p = Parameter((2, 2), symmetric=True, value=[[1, 1], [-1, -1]])
        self.assertEqual(str(cm.exception), "Parameter value must be symmetric.")
Esempio n. 10
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 def test_parameter_problems(self):
     """Test problems with parameters.
     """
     p1 = Parameter()
     p2 = Parameter(3, sign="negative")
     p3 = Parameter(4, 4, sign="positive")
     p = Problem(Maximize(p1*self.a), [self.a + p1 <= p2, self.b <= p3 + p3 + 2])
     p1.value = 2
     p2.value = -numpy.ones((3,1))
     p3.value = numpy.ones((4, 4))
     result = p.solve()
     self.assertAlmostEqual(result, -6)
Esempio n. 11
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 def test_parameter_problems(self):
     """Test problems with parameters.
     """
     p1 = Parameter()
     p2 = Parameter(3, sign="negative")
     p3 = Parameter(4, 4, sign="positive")
     p = Problem(Maximize(p1*self.a), [self.a + p1 <= p2, self.b <= p3 + p3 + 2])
     p1.value = 2
     p2.value = -numpy.ones((3,1))
     p3.value = numpy.ones((4, 4))
     result = p.solve()
     self.assertAlmostEqual(result, -6)
Esempio n. 12
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    def test_psd_nsd_parameters(self) -> None:
        # Test valid rank-deficeint PSD parameter.
        np.random.seed(42)
        a = np.random.normal(size=(100, 95))
        a2 = a.dot(a.T)  # This must be a PSD matrix.
        p = Parameter((100, 100), PSD=True)
        p.value = a2
        self.assertItemsAlmostEqual(p.value, a2, places=10)

        # Test positive definite matrix with non-distinct eigenvalues
        m, n = 10, 5
        A = np.random.randn(
            m, n) + 1j * np.random.randn(m, n)  # a random complex matrix
        A = np.dot(A.T.conj(),
                   A)  # a random Hermitian positive definite matrix
        A = np.vstack([
            np.hstack([np.real(A), -np.imag(A)]),
            np.hstack([np.imag(A), np.real(A)])
        ])

        p = Parameter(shape=(2 * n, 2 * n), PSD=True)
        p.value = A
        self.assertItemsAlmostEqual(p.value, A)

        # Test arithmetic.
        p = Parameter(shape=(2, 2), PSD=True)
        self.assertTrue((2 * p).is_psd())
        self.assertTrue((p + p).is_psd())
        self.assertTrue((-p).is_nsd())
        self.assertTrue(((-2) * (-p)).is_psd())

        # Test invalid PSD and NSD parameters
        n = 5
        P = Parameter(shape=(n, n), PSD=True)
        N = Parameter(shape=(n, n), NSD=True)
        np.random.randn(0)
        U = np.random.randn(n, n)
        U = U @ U.T
        (evals, U) = np.linalg.eigh(U)  # U is now an orthogonal matrix
        v1 = np.array([3, 2, 1, 1e-8, -1])
        v2 = np.array([3, 2, 2, 1e-6, -1])
        v3 = np.array([3, 2, 2, 1e-4, -1e-6])
        v4 = np.array([-1, 3, 0, 0, 0])
        vs = [v1, v2, v3, v4]
        for vi in vs:
            with self.assertRaises(Exception) as cm:
                P.value = U @ np.diag(vi) @ U.T
            self.assertEqual(str(cm.exception),
                             "Parameter value must be positive semidefinite.")
            with self.assertRaises(Exception) as cm:
                N.value = -U @ np.diag(vi) @ U.T
            self.assertEqual(str(cm.exception),
                             "Parameter value must be negative semidefinite.")
Esempio n. 13
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    def test_parameters(self):
        p = Parameter(name='p')
        self.assertEqual(p.name(), "p")
        self.assertEqual(p.size, (1, 1))

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = 1
        self.assertEqual(str(cm.exception),
                         "Invalid dimensions (1, 1) for Parameter value.")

        val = -np.ones((4, 3))
        val[0, 0] = 2

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception),
                         "Invalid sign for Parameter value.")

        p = Parameter(4, 3, sign="negative")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception),
                         "Invalid sign for Parameter value.")

        # No error for unknown sign.
        p = Parameter(4, 3)
        p.value = val

        # Initialize a parameter with a value.
        p = Parameter(value=10)
        self.assertEqual(p.value, 10)

        # Test assigning None.
        p.value = 10
        p.value = None
        assert p.value is None

        with self.assertRaises(Exception) as cm:
            p = Parameter(2, 1, sign="negative", value=[2, 1])
        self.assertEqual(str(cm.exception),
                         "Invalid sign for Parameter value.")

        with self.assertRaises(Exception) as cm:
            p = Parameter(4, 3, sign="positive", value=[1, 2])
        self.assertEqual(str(cm.exception),
                         "Invalid dimensions (2, 1) for Parameter value.")

        # Test repr.
        p = Parameter(4, 3, sign="negative")
        self.assertEqual(repr(p), 'Parameter(4, 3, sign="NEGATIVE")')
Esempio n. 14
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    def test_presolve_parameters(self):
        """Test presolve with parameters.
        """
        # Test with parameters.
        gamma = Parameter(sign="positive")
        x = Variable()
        obj = Minimize(x)
        prob = Problem(obj, [gamma == 1, x >= 0])
        gamma.value = 0
        prob.solve(solver=s.SCS)
        self.assertEqual(prob.status, s.INFEASIBLE)

        gamma.value = 1
        prob.solve(solver=s.CVXOPT)
        self.assertEqual(prob.status, s.OPTIMAL)
Esempio n. 15
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    def test_presolve_parameters(self):
        """Test presolve with parameters.
        """
        # Test with parameters.
        gamma = Parameter(sign="positive")
        x = Variable()
        obj = Minimize(x)
        prob = Problem(obj, [gamma == 1, x >= 0])
        gamma.value = 0
        prob.solve(solver=s.SCS)
        self.assertEqual(prob.status, s.INFEASIBLE)

        gamma.value = 1
        prob.solve(solver=s.CVXOPT)
        self.assertEqual(prob.status, s.OPTIMAL)
Esempio n. 16
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    def test_div_expression(self):
        # Vectors
        exp = self.x/2
        self.assertEqual(exp.curvature, u.Curvature.AFFINE_KEY)
        self.assertEqual(exp.sign, u.Sign.UNKNOWN_KEY)
        self.assertEqual(exp.canonical_form[0].size, (2,1))
        self.assertEqual(exp.canonical_form[1], [])
        # self.assertEqual(exp.name(), c.name() + " * " + self.x.name())
        self.assertEqual(exp.size, (2,1))

        with self.assertRaises(Exception) as cm:
            (self.x/[2,2,3])
        print cm.exception
        self.assertEqual(str(cm.exception), "Can only divide by a scalar constant.")

        # Constant expressions.
        c = Constant(2)
        exp = c/(3 - 5)
        self.assertEqual(exp.curvature, u.Curvature.CONSTANT_KEY)
        self.assertEqual(exp.size, (1,1))
        self.assertEqual(exp.sign, u.Sign.NEGATIVE_KEY)

        # Parameters.
        p = Parameter(sign="positive")
        exp = 2/p
        p.value = 2
        self.assertEquals(exp.value, 1)
Esempio n. 17
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    def test_broadcast_mul(self) -> None:
        """Test multiply broadcasting.
        """
        y = Parameter((3, 1))
        z = Variable((1, 3))
        y.value = np.arange(3)[:, None]
        z.value = (np.arange(3) - 1)[None, :]
        expr = cp.multiply(y, z)
        self.assertItemsAlmostEqual(expr.value, y.value * z.value)

        prob = cp.Problem(cp.Minimize(cp.sum(expr)), [z == z.value])
        prob.solve(solver=cp.SCS)
        self.assertItemsAlmostEqual(expr.value, y.value * z.value)

        np.random.seed(0)
        m, n = 3, 4
        A = np.random.rand(m, n)

        col_scale = Variable(n)

        with self.assertRaises(ValueError) as cm:
            cp.multiply(A, col_scale)
        self.assertEqual(str(cm.exception),
                         "Cannot broadcast dimensions  (3, 4) (4,)")

        col_scale = Variable([1, n])
        C = cp.multiply(A, col_scale)
        self.assertEqual(C.shape, (m, n))

        row_scale = Variable([m, 1])
        R = cp.multiply(A, row_scale)
        self.assertEqual(R.shape, (m, n))
Esempio n. 18
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    def test_div_expression(self):
        # Vectors
        exp = self.x / 2
        self.assertEqual(exp.curvature, u.Curvature.AFFINE_KEY)
        self.assertEqual(exp.sign, u.Sign.UNKNOWN_KEY)
        self.assertEqual(exp.canonical_form[0].size, (2, 1))
        self.assertEqual(exp.canonical_form[1], [])
        # self.assertEqual(exp.name(), c.name() + " * " + self.x.name())
        self.assertEqual(exp.size, (2, 1))

        with self.assertRaises(Exception) as cm:
            (self.x / [2, 2, 3])
        print cm.exception
        self.assertEqual(str(cm.exception),
                         "Can only divide by a scalar constant.")

        # Constant expressions.
        c = Constant(2)
        exp = c / (3 - 5)
        self.assertEqual(exp.curvature, u.Curvature.CONSTANT_KEY)
        self.assertEqual(exp.size, (1, 1))
        self.assertEqual(exp.sign, u.Sign.NEGATIVE_KEY)

        # Parameters.
        p = Parameter(sign="positive")
        exp = 2 / p
        p.value = 2
        self.assertEquals(exp.value, 1)
Esempio n. 19
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    def test_huber(self):
        # Valid.
        huber(self.x, 1)

        with self.assertRaises(Exception) as cm:
            huber(self.x, -1)
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        with self.assertRaises(Exception) as cm:
            huber(self.x, [1,1])
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        # M parameter.
        M = Parameter(sign="positive")
        # Valid.
        huber(self.x, M)
        M.value = 1
        self.assertAlmostEquals(huber(2, M).value, 3)
        # Invalid.
        M = Parameter(sign="negative")
        with self.assertRaises(Exception) as cm:
            huber(self.x, M)
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")
Esempio n. 20
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    def test_huber(self):
        # Valid.
        huber(self.x, 1)

        with self.assertRaises(Exception) as cm:
            huber(self.x, -1)
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        with self.assertRaises(Exception) as cm:
            huber(self.x, [1,1])
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        # M parameter.
        M = Parameter(sign="positive")
        # Valid.
        huber(self.x, M)
        M.value = 1
        self.assertAlmostEquals(huber(2, M).value, 3)
        # Invalid.
        M = Parameter(sign="negative")
        with self.assertRaises(Exception) as cm:
            huber(self.x, M)
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")
    def test_broadcast_add(self):
        """Test addition broadcasting.
        """
        y = Parameter((3, 1))
        z = Variable((1, 3))
        y.value = np.arange(3)[:, None]
        z.value = (np.arange(3) - 1)[None, :]
        expr = y + z
        self.assertItemsAlmostEqual(expr.value, y.value + z.value)

        prob = cp.Problem(cp.Minimize(cp.sum(expr)), [z == z.value])
        prob.solve()
        self.assertItemsAlmostEqual(expr.value, y.value + z.value)

        np.random.seed(0)
        m, n = 3, 4
        A = np.random.rand(m, n)

        col_scale = Variable(n)

        with self.assertRaises(ValueError) as cm:
            A + col_scale
        self.assertEqual(str(cm.exception),
                         "Cannot broadcast dimensions  (3, 4) (4,)")

        col_scale = Variable([1, n])
        C = A + col_scale
        self.assertEqual(C.shape, (m, n))

        row_scale = Variable([m, 1])
        R = A + row_scale
        self.assertEqual(R.shape, (m, n))
Esempio n. 22
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    def test_parameters(self):
        p = Parameter(name='p')
        self.assertEqual(p.name(), "p")
        self.assertEqual(p.size, (1, 1))

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = 1
        self.assertEqual(str(cm.exception), "Invalid dimensions (1, 1) for Parameter value.")

        val = -np.ones((4, 3))
        val[0, 0] = 2

        p = Parameter(4, 3, sign="positive")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception), "Invalid sign for Parameter value.")

        p = Parameter(4, 3, sign="negative")
        with self.assertRaises(Exception) as cm:
            p.value = val
        self.assertEqual(str(cm.exception), "Invalid sign for Parameter value.")

        # No error for unknown sign.
        p = Parameter(4, 3)
        p.value = val

        # Initialize a parameter with a value.
        p = Parameter(value=10)
        self.assertEqual(p.value, 10)

        # Test assigning None.
        p.value = 10
        p.value = None
        assert p.value is None

        with self.assertRaises(Exception) as cm:
            p = Parameter(2, 1, sign="negative", value=[2, 1])
        self.assertEqual(str(cm.exception), "Invalid sign for Parameter value.")

        with self.assertRaises(Exception) as cm:
            p = Parameter(4, 3, sign="positive", value=[1, 2])
        self.assertEqual(str(cm.exception), "Invalid dimensions (2, 1) for Parameter value.")

        # Test repr.
        p = Parameter(4, 3, sign="negative")
        self.assertEqual(repr(p), 'Parameter(4, 3, sign="NEGATIVE")')
Esempio n. 23
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 def test_1D_array(self):
     """Test NumPy 1D arrays as constants.
     """
     c = np.array([1, 2])
     p = Parameter(2)
     p.value = [1, 1]
     self.assertEquals((c * p).value, 3)
     self.assertEqual((c * self.x).size, (1, 1))
Esempio n. 24
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 def test_1D_array(self):
     """Test NumPy 1D arrays as constants.
     """
     c = np.array([1, 2])
     p = Parameter(2)
     p.value = [1, 1]
     self.assertEqual((c*p).value, 3)
     self.assertEqual((c*self.x).size, (1, 1))
 def test_1D_array(self):
     """Test NumPy 1D arrays as constants.
     """
     c = np.array([1, 2])
     p = Parameter(2)
     p.value = [1, 1]
     self.assertEqual((c @ p).value, 3)
     self.assertEqual((c @ self.x).shape, tuple())
    def test_div_expression(self):
        # Vectors
        exp = self.x / 2
        self.assertEqual(exp.curvature, s.AFFINE)
        self.assertEqual(exp.sign, s.UNKNOWN)
        self.assertEqual(exp.canonical_form[0].size, (2, 1))
        self.assertEqual(exp.canonical_form[1], [])
        # self.assertEqual(exp.name(), c.name() + " * " + self.x.name())
        self.assertEqual(exp.size, (2, 1))

        with self.assertRaises(Exception) as cm:
            (self.x / [2, 2, 3])
        print(cm.exception)
        self.assertEqual(str(cm.exception),
                         "Can only divide by a scalar constant.")

        # Constant expressions.
        c = Constant(2)
        exp = c / (3 - 5)
        self.assertEqual(exp.curvature, s.CONSTANT)
        self.assertEqual(exp.size, (1, 1))
        self.assertEqual(exp.sign, s.NEGATIVE)

        # Parameters.
        p = Parameter(sign="positive")
        exp = 2 / p
        p.value = 2
        self.assertEqual(exp.value, 1)

        rho = Parameter(sign="positive")
        rho.value = 1

        self.assertEqual(rho.sign, s.POSITIVE)
        self.assertEqual(Constant(2).sign, s.POSITIVE)
        self.assertEqual((Constant(2) / Constant(2)).sign, s.POSITIVE)
        self.assertEqual((Constant(2) * rho).sign, s.POSITIVE)
        self.assertEqual((rho / 2).sign, s.POSITIVE)
Esempio n. 27
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    def test_div_expression(self):
        # Vectors
        exp = self.x/2
        self.assertEqual(exp.curvature, s.AFFINE)
        self.assertEqual(exp.sign, s.UNKNOWN)
        self.assertEqual(exp.canonical_form[0].size, (2, 1))
        self.assertEqual(exp.canonical_form[1], [])
        # self.assertEqual(exp.name(), c.name() + " * " + self.x.name())
        self.assertEqual(exp.size, (2, 1))

        with self.assertRaises(Exception) as cm:
            (self.x/[2, 2, 3])
        print(cm.exception)
        self.assertEqual(str(cm.exception), "Can only divide by a scalar constant.")

        # Constant expressions.
        c = Constant(2)
        exp = c/(3 - 5)
        self.assertEqual(exp.curvature, s.CONSTANT)
        self.assertEqual(exp.size, (1, 1))
        self.assertEqual(exp.sign, s.NEGATIVE)

        # Parameters.
        p = Parameter(sign="positive")
        exp = 2/p
        p.value = 2
        self.assertEqual(exp.value, 1)

        rho = Parameter(sign="positive")
        rho.value = 1

        self.assertEqual(rho.sign, s.POSITIVE)
        self.assertEqual(Constant(2).sign, s.POSITIVE)
        self.assertEqual((Constant(2)/Constant(2)).sign, s.POSITIVE)
        self.assertEqual((Constant(2)*rho).sign, s.POSITIVE)
        self.assertEqual((rho/2).sign, s.POSITIVE)
Esempio n. 28
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    def test_partial_optimize_params(self):
        """Test partial optimize with parameters.
        """
        x, y = Variable(1), Variable(1)
        gamma = Parameter()
        # Solve the (simple) two-stage problem by "combining" the two stages (i.e., by solving a single linear program)
        p1 = Problem(Minimize(x+y), [x+y>=gamma, y>=4, x>=5])
        gamma.value = 3
        p1.solve()

        # Solve the two-stage problem via partial_optimize
        p2 = Problem(Minimize(y), [x+y>=gamma, y>=4])
        g = partial_optimize(p2, [y], [x])
        p3 = Problem(Minimize(x+g), [x>=5])
        p3.solve()
        self.assertAlmostEqual(p1.value, p3.value)
Esempio n. 29
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    def test_1D_array(self):
        """Test NumPy 1D arrays as constants.
        """
        c = np.array([1,2])
        p = Parameter(2)

        with warnings.catch_warnings(record=True) as w:
            # Cause all warnings to always be triggered.
            warnings.simplefilter("always")
            # Trigger a warning.
            Constant(c)
            self.x + c
            p.value = c
            # Verify some things
            self.assertEqual(len(w), 3)
            for warning in w:
                self.assertEqual(str(warning.message), "NumPy 1D arrays are treated as column vectors.")
Esempio n. 30
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    def test_huber(self):
        # Valid.
        huber(self.x, 1)

        with self.assertRaises(Exception) as cm:
            huber(self.x, -1)
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        with self.assertRaises(Exception) as cm:
            huber(self.x, [1,1])
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        # M parameter.
        M = Parameter(sign="positive")
        # Valid.
        huber(self.x, M)
        M.value = 1
        self.assertAlmostEquals(huber(2, M).value, 3)
        # Invalid.
        M = Parameter(sign="negative")
        with self.assertRaises(Exception) as cm:
            huber(self.x, M)
        self.assertEqual(str(cm.exception),
            "M must be a non-negative scalar constant.")

        # Test copy with args=None
        atom = huber(self.x, 2)
        copy = atom.copy()
        self.assertTrue(type(copy) is type(atom))
        # A new object is constructed, so copy.args == atom.args but copy.args
        # is not atom.args.
        self.assertEqual(copy.args, atom.args)
        self.assertFalse(copy.args is atom.args)
        # As get_data() returns a Constant, we have to check the value
        self.assertEqual(copy.get_data().value, atom.get_data().value)
        # Test copy with new args
        copy = atom.copy(args=[self.y])
        self.assertTrue(type(copy) is type(atom))
        self.assertTrue(copy.args[0] is self.y)
        self.assertEqual(copy.get_data().value, atom.get_data().value)
Esempio n. 31
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    def test_huber(self):
        # Valid.
        cp.huber(self.x, 1)

        with self.assertRaises(Exception) as cm:
            cp.huber(self.x, -1)
        self.assertEqual(str(cm.exception),
                         "M must be a non-negative scalar constant.")

        with self.assertRaises(Exception) as cm:
            cp.huber(self.x, [1, 1])
        self.assertEqual(str(cm.exception),
                         "M must be a non-negative scalar constant.")

        # M parameter.
        M = Parameter(nonneg=True)
        # Valid.
        cp.huber(self.x, M)
        M.value = 1
        self.assertAlmostEqual(cp.huber(2, M).value, 3)
        # Invalid.
        M = Parameter(nonpos=True)
        with self.assertRaises(Exception) as cm:
            cp.huber(self.x, M)
        self.assertEqual(str(cm.exception),
                         "M must be a non-negative scalar constant.")

        # Test copy with args=None
        atom = cp.huber(self.x, 2)
        copy = atom.copy()
        self.assertTrue(type(copy) is type(atom))
        # A new object is constructed, so copy.args == atom.args but copy.args
        # is not atom.args.
        self.assertEqual(copy.args, atom.args)
        self.assertFalse(copy.args is atom.args)
        # As get_data() returns a Constant, we have to check the value
        self.assertEqual(copy.get_data()[0].value, atom.get_data()[0].value)
        # Test copy with new args
        copy = atom.copy(args=[self.y])
        self.assertTrue(type(copy) is type(atom))
        self.assertTrue(copy.args[0] is self.y)
        self.assertEqual(copy.get_data()[0].value, atom.get_data()[0].value)
Esempio n. 32
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 def test_get_coefficients(self):
     """Test the get_coefficients function.
     """
     size = (5, 4)
     # Eye
     x = create_var(size)
     coeffs = get_coefficients(x)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(id_, x.data)
     self.assertItemsAlmostEqual(mat.todense(), sp.eye(20).todense())
     # Eye with scalar mult.
     x = create_var(size)
     A = create_const(5, (1, 1))
     coeffs = get_coefficients(mul_expr(A, x, size))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertItemsAlmostEqual(mat.todense(), 5 * sp.eye(20).todense())
     # Promoted
     x = create_var((1, 1))
     coeffs = get_coefficients(promote(x, size))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (20, 1))
     self.assertItemsAlmostEqual(mat, np.ones((20, 1)))
     # Normal
     size = (5, 5)
     x = create_var((5, 1))
     A = create_const(np.ones(size), size)
     coeffs = get_coefficients(mul_expr(A, x, (5, 1)))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (5, 5))
     self.assertItemsAlmostEqual(mat.todense(), A.data)
     # Blocks
     size = (5, 5)
     x = create_var(size)
     A = create_const(np.ones(size), size)
     coeffs = get_coefficients(mul_expr(A, x, size))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (25, 25))
     self.assertItemsAlmostEqual(
         mat.todense(),
         sp.block_diag(5 * [np.ones(size)]).todense())
     # Scalar constant
     size = (1, 1)
     A = create_const(5, size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(intf.size(mat), (1, 1))
     self.assertEqual(mat, 5)
     # Dense constant
     size = (5, 4)
     A = create_const(np.ones(size), size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (size[0] * size[1], 1))
     self.assertItemsAlmostEqual(mat, np.ones(size))
     # Sparse constant
     size = (5, 5)
     A = create_const(sp.eye(5), size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (size[0] * size[1], 1))
     self.assertItemsAlmostEqual(mat, sp.eye(5).todense())
     # Parameter
     size = (5, 4)
     param = Parameter(*size)
     param.value = np.ones(size)
     A = create_param(param, size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (size[0] * size[1], 1))
     self.assertItemsAlmostEqual(mat, param.value)
Esempio n. 33
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 def test_index(self):
     """Test the get_coefficients function for index.
     """
     size = (5, 4)
     # Eye
     key = (slice(0,2,None), slice(0,2,None))
     x = create_var(size)
     expr = index(x, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(id_, x.data)
     self.assertEqual(mat.shape, (4, 20))
     test_mat = np.mat(range(20)).T
     self.assertItemsAlmostEqual((mat*test_mat).reshape((2, 2), order='F'),
         test_mat.reshape(size, order='F')[key])
     # Eye with scalar mult.
     key = (slice(0,2,None), slice(0,2,None))
     x = create_var(size)
     A = create_const(5, (1, 1))
     expr = mul_expr(A, x, size)
     expr = index(expr, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     test_mat = np.mat(range(20)).T
     self.assertItemsAlmostEqual((mat*test_mat).reshape((2, 2), order='F'),
         5*test_mat.reshape(size, order='F')[key])
     # Promoted
     key = (slice(0,2,None), slice(0,2,None))
     x = create_var((1, 1))
     value = np.array(range(20)).reshape(size)
     A = create_const(value, size)
     prom_x = promote(x, (size[1], 1))
     expr = mul_expr(A, diag_vec(prom_x), size)
     expr = index(expr, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (4, 1))
     self.assertItemsAlmostEqual(mat, value[key])
     # Normal
     size = (5, 5)
     key = (slice(0,2,None), slice(0,1,None))
     x = create_var((5, 1))
     A = create_const(np.ones(size), size)
     expr = mul_expr(A, x, (5, 1))
     expr = index(expr, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 5))
     self.assertItemsAlmostEqual(mat.todense(), A.data[slice(0,2,None)])
     # Blocks
     size = (5, 5)
     key = (slice(0,2,None), slice(0,2,None))
     x = create_var(size)
     value = np.array(range(25)).reshape(size)
     A = create_const(value, size)
     expr = mul_expr(A, x, size)
     expr = index(expr, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (4, 25))
     test_mat = np.mat(range(25)).T
     self.assertItemsAlmostEqual((mat*test_mat).reshape((2, 2), order='F'),
         (A.data*test_mat.reshape(size, order='F'))[key])
     # Scalar constant
     size = (1, 1)
     A = create_const(5, size)
     key = (slice(0,1,None), slice(0,1,None))
     expr = index(A, (1, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(intf.size(mat), (1, 1))
     self.assertEqual(mat, 5)
     # Dense constant
     size = (5, 4)
     key = (slice(0,2,None), slice(0,1,None))
     value = np.array(range(20)).reshape(size)
     A = create_const(value, size)
     expr = index(A, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 1))
     self.assertItemsAlmostEqual(mat, value[key])
     # Sparse constant
     size = (5, 5)
     key = (slice(0,2,None), slice(0,1,None))
     A = create_const(sp.eye(5), size)
     expr = index(A, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 1))
     self.assertItemsAlmostEqual(mat, sp.eye(5).todense()[key])
     # Parameter
     size = (5, 4)
     key = (slice(0,2,None), slice(0,1,None))
     param = Parameter(*size)
     value = np.array(range(20)).reshape(size)
     param.value = value
     A = create_param(param, size)
     expr = index(A, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 1))
     self.assertItemsAlmostEqual(mat, param.value[key])
Esempio n. 34
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 def test_get_coefficients(self):
     """Test the get_coefficients function.
     """
     size = (5, 4)
     # Eye
     x = create_var(size)
     coeffs = get_coefficients(x)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(id_, x.data)
     self.assertItemsAlmostEqual(mat.todense(), sp.eye(20).todense())
     # Eye with scalar mult.
     x = create_var(size)
     A = create_const(5, (1, 1))
     coeffs = get_coefficients(mul_expr(A, x, size))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertItemsAlmostEqual(mat.todense(), 5*sp.eye(20).todense())
     # Promoted
     x = create_var((1, 1))
     coeffs = get_coefficients(promote(x, size))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (20, 1))
     self.assertItemsAlmostEqual(mat, np.ones((20, 1)))
     # Normal
     size = (5, 5)
     x = create_var((5, 1))
     A = create_const(np.ones(size), size)
     coeffs = get_coefficients(mul_expr(A, x, (5, 1)))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (5, 5))
     self.assertItemsAlmostEqual(mat.todense(), A.data)
     # Blocks
     size = (5, 5)
     x = create_var(size)
     A = create_const(np.ones(size), size)
     coeffs = get_coefficients(mul_expr(A, x, size))
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (25, 25))
     self.assertItemsAlmostEqual(mat.todense(),
      sp.block_diag(5*[np.ones(size)]).todense())
     # Scalar constant
     size = (1, 1)
     A = create_const(5, size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(intf.size(mat), (1, 1))
     self.assertEqual(mat, 5)
     # Dense constant
     size = (5, 4)
     A = create_const(np.ones(size), size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (size[0]*size[1], 1))
     self.assertItemsAlmostEqual(mat, np.ones(size))
     # Sparse constant
     size = (5, 5)
     A = create_const(sp.eye(5), size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (size[0]*size[1], 1))
     self.assertItemsAlmostEqual(mat, sp.eye(5).todense())
     # Parameter
     size = (5, 4)
     param = Parameter(*size)
     param.value = np.ones(size)
     A = create_param(param, size)
     coeffs = get_coefficients(A)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (size[0]*size[1], 1))
     self.assertItemsAlmostEqual(mat, param.value)
Esempio n. 35
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 def test_index(self):
     """Test the get_coefficients function for index.
     """
     size = (5, 4)
     # Eye
     key = (slice(0, 2, None), slice(0, 2, None))
     x = create_var(size)
     expr = index(x, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(id_, x.data)
     self.assertEqual(mat.shape, (4, 20))
     test_mat = np.mat(range(20)).T
     self.assertItemsAlmostEqual((mat * test_mat).reshape((2, 2),
                                                          order='F'),
                                 test_mat.reshape(size, order='F')[key])
     # Eye with scalar mult.
     key = (slice(0, 2, None), slice(0, 2, None))
     x = create_var(size)
     A = create_const(5, (1, 1))
     expr = mul_expr(A, x, size)
     expr = index(expr, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     test_mat = np.mat(range(20)).T
     self.assertItemsAlmostEqual((mat * test_mat).reshape(
         (2, 2), order='F'), 5 * test_mat.reshape(size, order='F')[key])
     # Promoted
     key = (slice(0, 2, None), slice(0, 2, None))
     x = create_var((1, 1))
     value = np.array(range(20)).reshape(size)
     A = create_const(value, size)
     prom_x = promote(x, (size[1], 1))
     expr = mul_expr(A, diag_vec(prom_x), size)
     expr = index(expr, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (4, 1))
     self.assertItemsAlmostEqual(mat, value[key])
     # Normal
     size = (5, 5)
     key = (slice(0, 2, None), slice(0, 1, None))
     x = create_var((5, 1))
     A = create_const(np.ones(size), size)
     expr = mul_expr(A, x, (5, 1))
     expr = index(expr, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 5))
     self.assertItemsAlmostEqual(mat.todense(), A.data[slice(0, 2, None)])
     # Blocks
     size = (5, 5)
     key = (slice(0, 2, None), slice(0, 2, None))
     x = create_var(size)
     value = np.array(range(25)).reshape(size)
     A = create_const(value, size)
     expr = mul_expr(A, x, size)
     expr = index(expr, (2, 2), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (4, 25))
     test_mat = np.mat(range(25)).T
     self.assertItemsAlmostEqual(
         (mat * test_mat).reshape((2, 2), order='F'),
         (A.data * test_mat.reshape(size, order='F'))[key])
     # Scalar constant
     size = (1, 1)
     A = create_const(5, size)
     key = (slice(0, 1, None), slice(0, 1, None))
     expr = index(A, (1, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(intf.size(mat), (1, 1))
     self.assertEqual(mat, 5)
     # Dense constant
     size = (5, 4)
     key = (slice(0, 2, None), slice(0, 1, None))
     value = np.array(range(20)).reshape(size)
     A = create_const(value, size)
     expr = index(A, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 1))
     self.assertItemsAlmostEqual(mat, value[key])
     # Sparse constant
     size = (5, 5)
     key = (slice(0, 2, None), slice(0, 1, None))
     A = create_const(sp.eye(5), size)
     expr = index(A, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 1))
     self.assertItemsAlmostEqual(mat, sp.eye(5).todense()[key])
     # Parameter
     size = (5, 4)
     key = (slice(0, 2, None), slice(0, 1, None))
     param = Parameter(*size)
     value = np.array(range(20)).reshape(size)
     param.value = value
     A = create_param(param, size)
     expr = index(A, (2, 1), key)
     coeffs = get_coefficients(expr)
     assert len(coeffs) == 1
     id_, mat = coeffs[0]
     self.assertEqual(mat.shape, (2, 1))
     self.assertItemsAlmostEqual(mat, param.value[key])
Esempio n. 36
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    def test_readme_examples(self):
        import cvxopt
        import numpy
        
        # Problem data.
        m = 30
        n = 20
        A = cvxopt.normal(m,n)
        b = cvxopt.normal(m)

        # Construct the problem.
        x = Variable(n)
        objective = Minimize(sum(square(A*x - b)))
        constraints = [0 <= x, x <= 1]
        p = Problem(objective, constraints)

        # The optimal objective is returned by p.solve().
        result = p.solve()
        # The optimal value for x is stored in x.value.
        print x.value
        # The optimal Lagrange multiplier for a constraint
        # is stored in constraint.dual_value.
        print constraints[0].dual_value

        ####################################################

        # Scalar variable.
        a = Variable()

        # Column vector variable of length 5.
        x = Variable(5)

        # Matrix variable with 4 rows and 7 columns.
        A = Variable(4,7)

        ####################################################

        # Positive scalar parameter.
        m = Parameter(sign="positive")

        # Column vector parameter with unknown sign (by default).
        c = Parameter(5)

        # Matrix parameter with negative entries.
        G = Parameter(4,7,sign="negative")

        # Assigns a constant value to G.
        G.value = -numpy.ones((4,7))

        # Raises an error for assigning a value with invalid sign.
        with self.assertRaises(Exception) as cm:
            G.value = numpy.ones((4,7))
        self.assertEqual(str(cm.exception), "Invalid sign for Parameter value.")

        ####################################################
        a = Variable()
        x = Variable(5)

        # expr is an Expression object after each assignment.
        expr = 2*x
        expr = expr - a
        expr = sum(expr) + norm2(x)

        ####################################################

        import numpy as np
        import cvxopt
        from multiprocessing import Pool

        # Problem data.
        n = 10
        m = 5
        A = cvxopt.normal(n,m)
        b = cvxopt.normal(n)
        gamma = Parameter(sign="positive")

        # Construct the problem.
        x = Variable(m)
        objective = Minimize(sum(square(A*x - b)) + gamma*norm1(x))
        p = Problem(objective)

        # Assign a value to gamma and find the optimal x.
        def get_x(gamma_value):
            gamma.value = gamma_value
            result = p.solve()
            return x.value

        gammas = np.logspace(-1, 2, num=2)
        # Serial computation.
        x_values = [get_x(value) for value in gammas]

        ####################################################
        n = 10

        mu = cvxopt.normal(1, n)
        sigma = cvxopt.normal(n,n)
        sigma = sigma.T*sigma
        gamma = Parameter(sign="positive")
        gamma.value = 1
        x = Variable(n)

        # Constants:
        # mu is the vector of expected returns.
        # sigma is the covariance matrix.
        # gamma is a Parameter that trades off risk and return.

        # Variables:
        # x is a vector of stock holdings as fractions of total assets.

        expected_return = mu*x
        risk = quad_form(x, sigma)

        objective = Maximize(expected_return - gamma*risk)
        p = Problem(objective, [sum(x) == 1])
        result = p.solve()

        # The optimal expected return.
        print expected_return.value

        # The optimal risk.
        print risk.value

    # # Risk return tradeoff curve
    # def test_risk_return_tradeoff(self):
    #     from math import sqrt
    #     from cvxopt import matrix
    #     from cvxopt.blas import dot
    #     from cvxopt.solvers import qp, options
    #     import scipy

    #     n = 4
    #     S = matrix( [[ 4e-2,  6e-3, -4e-3,   0.0 ],
    #                  [ 6e-3,  1e-2,  0.0,    0.0 ],
    #                  [-4e-3,  0.0,   2.5e-3, 0.0 ],
    #                  [ 0.0,   0.0,   0.0,    0.0 ]] )
    #     pbar = matrix([.12, .10, .07, .03])

    #     N = 100
    #     # CVXPY
    #     Sroot = numpy.asmatrix(scipy.linalg.sqrtm(S))
    #     x = Variable(n, name='x')
    #     mu = Parameter(name='mu')
    #     mu.value = 1 # TODO Parameter("positive")
    #     objective = Minimize(-pbar*x + mu*quad_over_lin(Sroot*x,1))
    #     constraints = [sum(x) == 1, x >= 0]
    #     p = Problem(objective, constraints)

    #     mus = [ 10**(5.0*t/N-1.0) for t in range(N) ]
    #     xs = []
    #     for mu_val in mus:
    #         mu.value = mu_val
    #         p.solve()
    #         xs.append(x.value)
    #     returns = [ dot(pbar,x) for x in xs ]
    #     risks = [ sqrt(dot(x, S*x)) for x in xs ]

    #     # QP solver
Esempio n. 37
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 def test_parameter_promotion(self):
     a = Parameter()
     exp = [[1,2],[3,4]]*a
     a.value = 2
     assert not (exp.value - 2*numpy.array([[1,2],[3,4]]).T).any()
Esempio n. 38
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 def test_parameter_promotion(self):
     a = Parameter()
     exp = [[1, 2], [3, 4]] * a
     a.value = 2
     assert not (exp.value - 2 * numpy.array([[1, 2], [3, 4]]).T).any()