def METHOD_NAME(result):
    """
    When constructing the dtype, take extra care to set values to
    np.Nan / -1 (for ints) as 0 might have a meaning
    """
    for field in result.dtype.names:
        if np.issubdtype(result.dtype[field], np.integer):
            result[field][:] = -1
        else:
            result[field][:] = np.nan