Python numpy.ma.zeros() Examples

def comp_g(dert__, odd):
    g__ = dert__[0]
    a__ = dert__[1:]

    # loop through each pair of comparands in a kernel
    dgy__ = ma.zeros(np.subtract(g.shape, rng))
    dgx__ = ma.zeros(np.subtract(g.shape, rng))
    for x_coeff, y_coeff, (ts, _ts) in zip(X_COEFFS[rng],
                                           Y_COEFFS[rng],
                                           TRANSLATING_SLICES_PAIRS_[rng]):
        # find angle differences
        da__ = angle_diff(a__[ts], a__[_ts])

        # compute dg: dg = g - _g * cos(da) at each position
        dg__ = g__[ts] - g__[_ts] * da__[1]

        # accumulate dgy, dgx
        dgx__ += dg__ * x_coeff
        dgy__ += dg__ * y_coeff

    gg__ = ma.hypot(dgy__, dgx__)

    return ma.stack((g__, gg__, dgy__, dgx__)) 

def empty(self, process_tile):
        """
        Return empty data.

        Parameters
        ----------
        process_tile : ``BufferedTile``
            must be member of process ``TilePyramid``

        Returns
        -------
        empty data : array
            empty array with data type given in output parameters
        """
        bands = (
            self.output_params["bands"]
            if "bands" in self.output_params
            else PNG_DEFAULT_PROFILE["count"]
        )
        return ma.masked_array(
            data=ma.zeros((bands, ) + process_tile.shape),
            mask=ma.zeros((bands, ) + process_tile.shape),
            dtype=PNG_DEFAULT_PROFILE["dtype"]
        ) 

def _draw_steps_post(self, renderer, gc, path, trans):
        vertices = self._xy
        steps = ma.zeros((2 * len(vertices) - 1, 2), np.float_)

        steps[::2, 0], steps[1:-1:2, 0] = vertices[:, 0], vertices[1:, 0]
        steps[0::2, 1], steps[1::2, 1] = vertices[:, 1], vertices[:-1, 1]

        path = Path(steps)
        path = path.transformed(self.get_transform())
        self._lineFunc(renderer, gc, path, IdentityTransform()) 

def test_duplicate_keys(self):
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        assert_raises(ValueError, join_by, ['a', 'b', 'b'], a, b) 

def _resize(masked, new_size):
    """
    Masked arrays can not be resized inplace, and `np.resize` and
    `ma.resize` are both incompatible with structured arrays.
    Therefore, we do all this.
    """
    new_array = ma.zeros((new_size,), dtype=masked.dtype)
    length = min(len(masked), new_size)
    new_array[:length] = masked[:length]

    return new_array 

def test_simple_flexible(self):
        # Test recursive_fill_fields on flexible-array
        a = np.array([(1, 10.), (2, 20.)], dtype=[('A', int), ('B', float)])
        b = np.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = np.array([(1, 10.), (2, 20.), (0, 0.)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_repack_fields(self):
        dt = np.dtype('u1,f4,i8', align=True)
        a = np.zeros(2, dtype=dt)

        assert_equal(repack_fields(dt), np.dtype('u1,f4,i8'))
        assert_equal(repack_fields(a).itemsize, 13)
        assert_equal(repack_fields(repack_fields(dt), align=True), dt)

        # make sure type is preserved
        dt = np.dtype((np.record, dt))
        assert_(repack_fields(dt).type is np.record) 

def test_masked_flexible(self):
        # Test recursive_fill_fields on masked flexible-array
        a = ma.array([(1, 10.), (2, 20.)], mask=[(0, 1), (1, 0)],
                     dtype=[('A', int), ('B', float)])
        b = ma.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = ma.array([(1, 10.), (2, 20.), (0, 0.)],
                           mask=[(0, 1), (1, 0), (0, 0)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_simple_flexible(self):
        # Test recursive_fill_fields on flexible-array
        a = np.array([(1, 10.), (2, 20.)], dtype=[('A', int), ('B', float)])
        b = np.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = np.array([(1, 10.), (2, 20.), (0, 0.)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_repack_fields(self):
        dt = np.dtype('u1,f4,i8', align=True)
        a = np.zeros(2, dtype=dt)

        assert_equal(repack_fields(dt), np.dtype('u1,f4,i8'))
        assert_equal(repack_fields(a).itemsize, 13)
        assert_equal(repack_fields(repack_fields(dt), align=True), dt)

        # make sure type is preserved
        dt = np.dtype((np.record, dt))
        assert_(repack_fields(dt).type is np.record) 

def create_arrays(self, nrows=0, config=None):
        """
        Create a new array to hold the data based on the current set
        of fields, and store them in the *array* and member variable.
        Any data in the existing array will be lost.

        *nrows*, if provided, is the number of rows to allocate.
        """
        if nrows is None:
            nrows = 0

        fields = self.fields

        if len(fields) == 0:
            array = np.recarray((nrows,), dtype='O')
            mask = np.zeros((nrows,), dtype='b')
        else:
            # for field in fields: field._setup(config)
            Field.uniqify_names(fields)

            dtype = []
            for x in fields:
                if x._unique_name == x.ID:
                    id = x.ID
                else:
                    id = (x._unique_name, x.ID)
                dtype.append((id, x.converter.format))

            array = np.recarray((nrows,), dtype=np.dtype(dtype))
            descr_mask = []
            for d in array.dtype.descr:
                new_type = (d[1][1] == 'O' and 'O') or 'bool'
                if len(d) == 2:
                    descr_mask.append((d[0], new_type))
                elif len(d) == 3:
                    descr_mask.append((d[0], new_type, d[2]))
            mask = np.zeros((nrows,), dtype=descr_mask)

        self.array = ma.array(array, mask=mask) 

def test_different_field_order(self):
        # gh-8940
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        # this should not give a FutureWarning:
        j = join_by(['c', 'b'], a, b, jointype='inner', usemask=False)
        assert_equal(j.dtype.names, ['b', 'c', 'a1', 'a2']) 

def test_different_field_order(self):
        # gh-8940
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        # this should not give a FutureWarning:
        j = join_by(['c', 'b'], a, b, jointype='inner', usemask=False)
        assert_equal(j.dtype.names, ['b', 'c', 'a1', 'a2']) 

def test_masked_flexible(self):
        # Test recursive_fill_fields on masked flexible-array
        a = ma.array([(1, 10.), (2, 20.)], mask=[(0, 1), (1, 0)],
                     dtype=[('A', int), ('B', float)])
        b = ma.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = ma.array([(1, 10.), (2, 20.), (0, 0.)],
                           mask=[(0, 1), (1, 0), (0, 0)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_simple_flexible(self):
        # Test recursive_fill_fields on flexible-array
        a = np.array([(1, 10.), (2, 20.)], dtype=[('A', int), ('B', float)])
        b = np.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = np.array([(1, 10.), (2, 20.), (0, 0.)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def _draw_steps_mid(self, renderer, gc, path, trans):
        vertices = self._xy
        steps = ma.zeros((2 * len(vertices), 2), np.float_)

        steps[1:-1:2, 0] = 0.5 * (vertices[:-1, 0] + vertices[1:, 0])
        steps[2::2, 0] = 0.5 * (vertices[:-1, 0] + vertices[1:, 0])
        steps[0, 0] = vertices[0, 0]
        steps[-1, 0] = vertices[-1, 0]
        steps[0::2, 1], steps[1::2, 1] = vertices[:, 1], vertices[:, 1]

        path = Path(steps)
        path = path.transformed(self.get_transform())
        self._lineFunc(renderer, gc, path, IdentityTransform()) 

def test_repack_fields(self):
        dt = np.dtype('u1,f4,i8', align=True)
        a = np.zeros(2, dtype=dt)

        assert_equal(repack_fields(dt), np.dtype('u1,f4,i8'))
        assert_equal(repack_fields(a).itemsize, 13)
        assert_equal(repack_fields(repack_fields(dt), align=True), dt)

        # make sure type is preserved
        dt = np.dtype((np.record, dt))
        assert_(repack_fields(dt).type is np.record) 

def _draw_steps_pre(self, renderer, gc, path, trans):
        vertices = self._xy
        steps = ma.zeros((2 * len(vertices) - 1, 2), np.float_)

        steps[0::2, 0], steps[1::2, 0] = vertices[:, 0], vertices[:-1, 0]
        steps[0::2, 1], steps[1:-1:2, 1] = vertices[:, 1], vertices[1:, 1]

        path = Path(steps)
        path = path.transformed(self.get_transform())
        self._lineFunc(renderer, gc, path, IdentityTransform()) 

def test_masked_flexible(self):
        # Test recursive_fill_fields on masked flexible-array
        a = ma.array([(1, 10.), (2, 20.)], mask=[(0, 1), (1, 0)],
                     dtype=[('A', int), ('B', float)])
        b = ma.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = ma.array([(1, 10.), (2, 20.), (0, 0.)],
                           mask=[(0, 1), (1, 0), (0, 0)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_simple_flexible(self):
        # Test recursive_fill_fields on flexible-array
        a = np.array([(1, 10.), (2, 20.)], dtype=[('A', int), ('B', float)])
        b = np.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = np.array([(1, 10.), (2, 20.), (0, 0.)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_duplicate_keys(self):
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        assert_raises(ValueError, join_by, ['a', 'b', 'b'], a, b) 

def test_different_field_order(self):
        # gh-8940
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        # this should not give a FutureWarning:
        j = join_by(['c', 'b'], a, b, jointype='inner', usemask=False)
        assert_equal(j.dtype.names, ['b', 'c', 'a1', 'a2']) 

def test_masked_flexible(self):
        # Test recursive_fill_fields on masked flexible-array
        a = ma.array([(1, 10.), (2, 20.)], mask=[(0, 1), (1, 0)],
                     dtype=[('A', int), ('B', float)])
        b = ma.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = ma.array([(1, 10.), (2, 20.), (0, 0.)],
                           mask=[(0, 1), (1, 0), (0, 0)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_simple_flexible(self):
        # Test recursive_fill_fields on flexible-array
        a = np.array([(1, 10.), (2, 20.)], dtype=[('A', int), ('B', float)])
        b = np.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = np.array([(1, 10.), (2, 20.), (0, 0.)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def get_hillas_mean(self):
        """This is a simple function to find the peak position of each image
        in an event which will be used later in the Xmax calculation. Peak is
        found by taking the average position of the n hottest pixels in the
        image.

        Parameters
        ----------

        Returns
        -------
            None

        """
        peak_x = np.zeros([len(self.pixel_x)])  # Create blank arrays for peaks
        # rather than a dict (faster)
        peak_y = np.zeros(peak_x.shape)
        peak_amp = np.zeros(peak_x.shape)

        # Loop over all tels to take weighted average of pixel
        # positions This loop could maybe be replaced by an array
        # operation by a numpy wizard
        # Maybe a vectorize?
        tel_num = 0

        for hillas in self.hillas_parameters:
            peak_x[tel_num] = hillas.x.to(u.rad).value  # Fill up array
            peak_y[tel_num] = hillas.y.to(u.rad).value
            peak_amp[tel_num] = hillas.intensity
            tel_num += 1

        self.peak_x = peak_x  # * unit # Add to class member
        self.peak_y = peak_y  # * unit
        self.peak_amp = peak_amp

    # This function would be useful elsewhere so probably be implemented in a
    # more general form 

def test_duplicate_keys(self):
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        assert_raises(ValueError, join_by, ['a', 'b', 'b'], a, b) 

def test_different_field_order(self):
        # gh-8940
        a = np.zeros(3, dtype=[('a', 'i4'), ('b', 'f4'), ('c', 'u1')])
        b = np.ones(3, dtype=[('c', 'u1'), ('b', 'f4'), ('a', 'i4')])
        # this should not give a FutureWarning:
        j = join_by(['c', 'b'], a, b, jointype='inner', usemask=False)
        assert_equal(j.dtype.names, ['b', 'c', 'a1', 'a2']) 

def test_masked_flexible(self):
        # Test recursive_fill_fields on masked flexible-array
        a = ma.array([(1, 10.), (2, 20.)], mask=[(0, 1), (1, 0)],
                     dtype=[('A', int), ('B', float)])
        b = ma.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = ma.array([(1, 10.), (2, 20.), (0, 0.)],
                           mask=[(0, 1), (1, 0), (0, 0)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_simple_flexible(self):
        # Test recursive_fill_fields on flexible-array
        a = np.array([(1, 10.), (2, 20.)], dtype=[('A', int), ('B', float)])
        b = np.zeros((3,), dtype=a.dtype)
        test = recursive_fill_fields(a, b)
        control = np.array([(1, 10.), (2, 20.), (0, 0.)],
                           dtype=[('A', int), ('B', float)])
        assert_equal(test, control) 

def test_repack_fields(self):
        dt = np.dtype('u1,f4,i8', align=True)
        a = np.zeros(2, dtype=dt)

        assert_equal(repack_fields(dt), np.dtype('u1,f4,i8'))
        assert_equal(repack_fields(a).itemsize, 13)
        assert_equal(repack_fields(repack_fields(dt), align=True), dt)

        # make sure type is preserved
        dt = np.dtype((np.record, dt))
        assert_(repack_fields(dt).type is np.record)