apexpy.apex.Apex.convert()

Complexity

Conditions

19

Size

Total Lines	102
Code Lines	43

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

# -*- coding: utf-8 -*-
    def convert(self, lat, lon, source, dest, height=0, datetime=None,
                precision=1e-10, ssheight=50 * 6371):
        """Converts between geodetic, modified apex, quasi-dipole and MLT.

        Parameters
        ----------
        lat : array_like
            Latitude in degrees
        lon : array_like
            Longitude in degrees or MLT in hours
        source : str
            Input coordinate system, accepts 'geo', 'apex', 'qd', or 'mlt'
        dest : str
            Output coordinate system, accepts 'geo', 'apex', 'qd', or 'mlt'
        height : array_like, optional
            Altitude in km
        datetime : :class:`datetime.datetime`
            Date and time for MLT conversions (required for MLT conversions)
        precision : float, optional
            Precision of output (degrees) when converting to geo. A negative
            value of this argument produces a low-precision calculation of
            geodetic lat/lon based only on their spherical harmonic
            representation.
            A positive value causes the underlying Fortran routine to iterate
            until feeding the output geo lat/lon into geo2qd (APXG2Q) reproduces
            the input QD lat/lon to within the specified precision (all
            coordinates being converted to geo are converted to QD first and
            passed through APXG2Q).
        ssheight : float, optional
            Altitude in km to use for converting the subsolar point from
            geographic to magnetic coordinates. A high altitude is used
            to ensure the subsolar point is mapped to high latitudes, which
            prevents the South-Atlantic Anomaly (SAA) from influencing the MLT.

        Returns
        -------
        lat : ndarray or float
            Converted latitude (if converting to MLT, output latitude is apex)
        lon : ndarray or float
            Converted longitude or MLT

        Raises
        ------
        ValueError
            For unknown source or destination coordinate system or a missing
            or badly formed latitude or datetime input

        """
        # Test the input values
        source = source.lower()
        dest = dest.lower()

        if source not in ['geo', 'apex', 'qd', 'mlt'] \
           or dest not in ['geo', 'apex', 'qd', 'mlt']:
            estr = 'Unknown coordinate transformation: {} -> {}'.format(source,
                                                                        dest)
            raise ValueError(estr)

        if datetime is None and ('mlt' in [source, dest]):
            raise ValueError('datetime must be given for MLT calculations')

        lat = helpers.checklat(lat)

        if source == dest:
            # The source and destination are the same, no conversion necessary
            return lat, lon
        else:
            # Select the correct conversion method
            if source == 'geo':
                if dest == 'qd':
                    lat, lon = self.geo2qd(lat, lon, height)
                else:
                    lat, lon = self.geo2apex(lat, lon, height)
                    if dest == 'mlt':
                        lon = self.mlon2mlt(lon, datetime, ssheight=ssheight)
            elif source == 'apex':
                if dest == 'geo':
                    lat, lon, _ = self.apex2geo(lat, lon, height,
                                                precision=precision)
                elif dest == 'qd':
                    lat, lon = self.apex2qd(lat, lon, height=height)
                elif dest == 'mlt':
                    lon = self.mlon2mlt(lon, datetime, ssheight=ssheight)
            elif source == 'qd':
                if dest == 'geo':
                    lat, lon, _ = self.qd2geo(lat, lon, height,
                                              precision=precision)
                else:
                    lat, lon = self.qd2apex(lat, lon, height=height)
                    if dest == 'mlt':
                        lon = self.mlon2mlt(lon, datetime, ssheight=ssheight)
            elif source == 'mlt':
                # From MLT means that the input latitude is assumed to be apex,
                # so we don't need to update latitude for apex conversions.
                lon = self.mlt2mlon(lon, datetime, ssheight=ssheight)
                if dest == 'geo':
                    lat, lon, _ = self.apex2geo(lat, lon, height,
                                                precision=precision)
                elif dest == 'qd':
                    lat, lon = self.apex2qd(lat, lon, height=height)

        return lat, lon