numpy/polynomial/tests/test_polyutils.py

"""Tests for polyutils module.

"""
import numpy as np
import numpy.polynomial.polyutils as pu
from numpy.testing import (
    assert_almost_equal, assert_raises, assert_equal, assert_,
    )


class TestMisc:

    def test_trimseq(self):
        tgt = [1]
        for num_trailing_zeros in range(5):
            res = pu.trimseq([1] + [0] * num_trailing_zeros)
            assert_equal(res, tgt)

    def test_trimseq_empty_input(self):
        for empty_seq in [[], np.array([], dtype=np.int32)]:
            assert_equal(pu.trimseq(empty_seq), empty_seq)

    def test_as_series(self):
        # check exceptions
        assert_raises(ValueError, pu.as_series, [[]])
        assert_raises(ValueError, pu.as_series, [[[1, 2]]])
        assert_raises(ValueError, pu.as_series, [[1], ['a']])
        # check common types
        types = ['i', 'd', 'O']
        for i in range(len(types)):
            for j in range(i):
                ci = np.ones(1, types[i])
                cj = np.ones(1, types[j])
                [resi, resj] = pu.as_series([ci, cj])
                assert_(resi.dtype.char == resj.dtype.char)
                assert_(resj.dtype.char == types[i])

    def test_trimcoef(self):
        coef = [2, -1, 1, 0]
        # Test exceptions
        assert_raises(ValueError, pu.trimcoef, coef, -1)
        # Test results
        assert_equal(pu.trimcoef(coef), coef[:-1])
        assert_equal(pu.trimcoef(coef, 1), coef[:-3])
        assert_equal(pu.trimcoef(coef, 2), [0])

    def test_vander_nd_exception(self):
        # n_dims != len(points)
        assert_raises(ValueError, pu._vander_nd, (), (1, 2, 3), [90])
        # n_dims != len(degrees)
        assert_raises(ValueError, pu._vander_nd, (), (), [90.65])
        # n_dims == 0
        assert_raises(ValueError, pu._vander_nd, (), (), [])

    def test_div_zerodiv(self):
        # c2[-1] == 0
        assert_raises(ZeroDivisionError, pu._div, pu._div, (1, 2, 3), [0])

    def test_pow_too_large(self):
        # power > maxpower
        assert_raises(ValueError, pu._pow, (), [1, 2, 3], 5, 4)

class TestDomain:

    def test_getdomain(self):
        # test for real values
        x = [1, 10, 3, -1]
        tgt = [-1, 10]
        res = pu.getdomain(x)
        assert_almost_equal(res, tgt)

        # test for complex values
        x = [1 + 1j, 1 - 1j, 0, 2]
        tgt = [-1j, 2 + 1j]
        res = pu.getdomain(x)
        assert_almost_equal(res, tgt)

    def test_mapdomain(self):
        # test for real values
        dom1 = [0, 4]
        dom2 = [1, 3]
        tgt = dom2
        res = pu.mapdomain(dom1, dom1, dom2)
        assert_almost_equal(res, tgt)

        # test for complex values
        dom1 = [0 - 1j, 2 + 1j]
        dom2 = [-2, 2]
        tgt = dom2
        x = dom1
        res = pu.mapdomain(x, dom1, dom2)
        assert_almost_equal(res, tgt)

        # test for multidimensional arrays
        dom1 = [0, 4]
        dom2 = [1, 3]
        tgt = np.array([dom2, dom2])
        x = np.array([dom1, dom1])
        res = pu.mapdomain(x, dom1, dom2)
        assert_almost_equal(res, tgt)

        # test that subtypes are preserved.
        class MyNDArray(np.ndarray):
            pass

        dom1 = [0, 4]
        dom2 = [1, 3]
        x = np.array([dom1, dom1]).view(MyNDArray)
        res = pu.mapdomain(x, dom1, dom2)
        assert_(isinstance(res, MyNDArray))

    def test_mapparms(self):
        # test for real values
        dom1 = [0, 4]
        dom2 = [1, 3]
        tgt = [1, .5]
        res = pu. mapparms(dom1, dom2)
        assert_almost_equal(res, tgt)

        # test for complex values
        dom1 = [0 - 1j, 2 + 1j]
        dom2 = [-2, 2]
        tgt = [-1 + 1j, 1 - 1j]
        res = pu.mapparms(dom1, dom2)
        assert_almost_equal(res, tgt)