apexpy.apex.Apex._map_EV_to_height()

Complexity

Conditions

11

Size

Total Lines	75
Code Lines	27

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

# -*- coding: utf-8 -*-
    def _map_EV_to_height(self, alat, alon, height, newheight, data, ev_flag):
        """Maps electric field related values to a desired height

        Parameters
        ----------
        alat : array-like
            Apex latitude in degrees.
        alon : array-like
            Apex longitude in degrees.
        height : array-like
            Current altitude in km.
        new_height : array-like
            Desired altitude to which EV values will be mapped in km.
        data : array-like
            3D value(s) for the electric field or electric drift
        ev_flag : str
           Specify if value is an electric field ('E') or electric drift ('V')

        Returns
        -------
        data_mapped : array-like
            Data mapped along the magnetic field from the old height to the
            new height.

        Raises
        ------
        ValueError
            If an unknown `ev_flag` or badly shaped data input is supplied.

        """
        # Ensure the E-V flag is correct
        ev_flag = ev_flag.upper()
        if ev_flag not in ['E', 'V']:
            raise ValueError('unknown electric field/drift flag')

        # Make sure data is array of correct shape
        if not (np.ndim(data) == 1
                and np.size(data) == 3) and not (np.ndim(data) == 2
                                                 and np.shape(data)[0] == 3):
            # Raise ValueError because if passing e.g. a (6,) ndarray the
            # reshape below will work even though the input is invalid
            raise ValueError('{:} must be (3, N) or (3,) ndarray'.format(
                ev_flag))

        data = np.reshape(data, (3, np.size(data) // 3))

        # Get the necessary base vectors at the current and new height
        v1 = list()
        v2 = list()
        for i, alt in enumerate([height, newheight]):
            _, _, _, _, _, _, d1, d2, _, e1, e2, _ = self.basevectors_apex(
                alat, alon, alt, coords='apex')

            if ev_flag == 'E' and i == 0 or ev_flag == 'V' and i == 1:
                v1.append(e1)
                v2.append(e2)
            else:
                v1.append(d1)
                v2.append(d2)

            # Make sure v1 and v2 have shape (3, N)
            v1[-1] = np.reshape(v1[-1], (3, v1[-1].size // 3))
            v2[-1] = np.reshape(v2[-1], (3, v2[-1].size // 3))

        # Take the dot product between the data value and each base vector
        # at the current height
        data1 = np.sum(data * v1[0], axis=0)
        data2 = np.sum(data * v2[0], axis=0)

        # Map the data to the new height, removing any axes of length 1
        # after the calculation
        data_mapped = np.squeeze(data1[np.newaxis, :] * v1[1]
                                 + data2[np.newaxis, :] * v2[1])

        return data_mapped