'Get array of 0 and 1 of len = len(self.data). If there is a missing
value at any attribute in indices return 0 for that instance.'

def get_valid_list(self, indices):

    if ((self.valid_data_array is None) or (len(self.valid_data_array) == 0)):
        return np.array([], np.bool)
    return np.all(self.valid_data_array[indices], axis=0)
