aacgmv2.wrapper.convert_latlon()

Complexity

Conditions

9

Size

Total Lines	95
Code Lines	37

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

# Copyright (C) 2019 NRL 
def convert_latlon(in_lat, in_lon, height, dtime, method_code="G2A"):
    """Converts between geomagnetic coordinates and AACGM coordinates

    Parameters
    ------------
    in_lat : (float)
        Input latitude in degrees N (code specifies type of latitude)
    in_lon : (float)
        Input longitude in degrees E (code specifies type of longitude)
    height : (float)
        Altitude above the surface of the earth in km
    dtime : (datetime)
        Datetime for magnetic field
    method_code : (str or int)
        Bit code or string denoting which type(s) of conversion to perform
        G2A        - geographic (geodetic) to AACGM-v2
        A2G        - AACGM-v2 to geographic (geodetic)
        TRACE      - use field-line tracing, not coefficients
        ALLOWTRACE - use trace only above 2000 km
        BADIDEA    - use coefficients above 2000 km
        GEOCENTRIC - assume inputs are geocentric w/ RE=6371.2
        (default is "G2A")

    Returns
    -------
    out_lat : (float)
        Output latitude in degrees N
    out_lon : (float)
        Output longitude in degrees E
    out_r : (float)
        Geocentric radial distance (R_Earth) or altitude above the surface of
        the Earth (km)

    Raises
    ------
    ValueError if input is incorrect
    TypeError or RuntimeError if unable to set AACGMV2 datetime

    """

    # Test time
    dtime = test_time(dtime)

    # Initialise output
    lat_out = np.nan
    lon_out = np.nan
    r_out = np.nan

    # Set the coordinate coversion method code in bits
    try:
        bit_code = convert_str_to_bit(method_code.upper())
    except AttributeError:
        bit_code = method_code

    if not isinstance(bit_code, int):
        raise ValueError("unknown method code {:}".format(method_code))

    # Test height that may or may not cause failure
    if not test_height(height, bit_code):
        return lat_out, lon_out, r_out

    # Test latitude range
    if abs(in_lat) > 90.0:
        # Allow latitudes with a small deviation from the maximum
        # (+/- 90 degrees) to be set to 90
        if abs(in_lat) > 90.1:
            raise ValueError('unrealistic latitude')
        in_lat = np.sign(in_lat) * 90.0

    # Constrain longitudes between -180 and 180
    in_lon = ((in_lon + 180.0) % 360.0) - 180.0

    # Set current date and time
    try:
        c_aacgmv2.set_datetime(dtime.year, dtime.month, dtime.day, dtime.hour,
                               dtime.minute, dtime.second)
    except TypeError as terr:
        raise TypeError("unable to set time for {:}: {:}".format(dtime, terr))
    except RuntimeError as rerr:
        raise RuntimeError("unable to set time for {:}: {:}".format(dtime,
                                                                    rerr))

    # convert location
    try:
        lat_out, lon_out, r_out = c_aacgmv2.convert(in_lat, in_lon, height,
                                                    bit_code)
    except:
        err = sys.exc_info()[0]
        estr = "unable to perform conversion at {:.1f},".format(in_lat)
        estr = "{:s}{:.1f} {:.1f} km, {:} ".format(estr, in_lon, height, dtime)
        estr = "{:s}using method {:}: {:}".format(estr, bit_code, err)
        aacgmv2.logger.warning(estr)
        pass

    return lat_out, lon_out, r_out