def _get_dims(data):
    """Get primary x-y dimensions of dataset

    """
    if 'XC' in data.dims:
        xdim = 'XC'
    elif 'XG' in data.dims:
        xdim = 'XG'
    else:
        xdim = 'x_km'
    if 'YC' in data.dims:
        ydim = 'YC'
    elif 'YG' in data.dims:
        ydim = 'YG'
    else:
        ydim = 'y_km'
    return ydim, xdim
