文件对象本身已经是可迭代的。
>>> f = open('1.txt')>>> f<_io.TextIOWrapper name='1.txt' encoding='UTF-8'>>>> next(f)'1,B,-0.0522642316338,0.997268450092n'>>> next(f)'2,B,-0.081127897359,2.05114559572n'用于
itertools.islice从可迭代对象中获取任意元素。
>>> f.seek(0)0>>> next(islice(f, 7, None))'8,A,-0.0518101108474,12.094341554n'
