# 如何对迭代器做切片操作
f = open('test.log')
# f.readlines() 一次性把文件读入到内存当中
# lines = list(f.readlines())
# print(lines[100:300])
# for line in f:
# print(line)
from itertools import islice
# 100-300行
lines = islice(f, 100, 300)
# 前300行
# lines = islice(f, 300)
# 300行到尾部
# lines = islice(f, 300, None)
# for line in lines:
# print(line)
l = range(20)
t = iter(l)
# print(list(t))
# islice 会消耗原来的迭代对象
for x in islice(t, 5, 10):
print(x)
for x in t:
print(x)