Function _get_coord_names

src/wrf/util.py:1131–1219

(wrfin, varname)

def _get_coord_names(wrfin, varname):

    # Need only the first real file
    if is_multi_file(wrfin):
        if not is_mapping(wrfin):
            wrfnc = next(iter(wrfin))
        else:
            entry = wrfin[next(iter(viewkeys(wrfin)))]
            return _get_coord_names(entry, varname)
    else:
        wrfnc = wrfin

    lat_coord = None
    lon_coord = None
    time_coord = None

    var = wrfnc.variables[varname]

    # WRF variables will have a coordinates attribute.  MET_EM files have
    # a stagger attribute which indicates the coordinate variable.
    try:
        # WRF files
        coord_attr = getattr(var, "coordinates")
    except AttributeError:

        if is_coordvar(varname):
            # Coordinate variable (most likely XLAT or XLONG)
            lat_coord, lon_coord = get_coord_pairs(varname)
            time_coord = None

            if has_time_coord(wrfnc):
                time_coord = "XTIME"

        elif is_time_coord_var(varname):
            lon_coord = None
            lat_coord = None
            time_coord = None
        else:
            try:
                # met_em files or old WRF files
                stag_attr = getattr(var, "stagger")
            except AttributeError:
                lon_coord = None
                lat_coord = None

                # Let's just check for xlat and xlong in this case
                if "XLAT" in wrfnc.variables:
                    lat_coord = "XLAT"
                    lon_coord = "XLONG"
            else:
                # For met_em files, use the stagger name to get the lat/lon var
                lat_coord = "XLAT_{}".format(stag_attr)
                lon_coord = "XLONG_{}".format(stag_attr)

                # If this coord name is missing, it might be an old WRF file
                if lat_coord not in wrfnc.variables:
                    lat_coord = None
                    lon_coord = None