python:_csv.Error: line contains NULL byte错误

#! /usr/bin/env python#coding=utf-8import networkx as nximport unicodecsv as csvpath="F:/Data/exe/marvel.csv"def graph_from_csv(path):    graph=nx.Graph(name="Heroic Social Network")    with open(path,"rU") as data:        reader=csv.reader(data)        for row in reader:            graph.add_edge(*row)    return graphgraph=graph_from_csv(path)#print(graph.order())#print(graph.size())#错误：_csv.Error: line contains NULL byte#翻译为：CSV错误：行包含空字节#之前用pandas,pd.read_csv(path)时，兼容path文件可以为除了csv的其他类型#这里的csv就不可以，读取的就是csv类型，新建一个csv文件就读入了。