文章内容
2021/3/26 14:26:35,作 者: 黄兵
Python Itertools 模块
Python 的 Itertools 模块是处理迭代器的工具集合。迭代器是一种可以在 for 循环语句（包括列表、元组和字典）中使用的数据类型。
使用 Itertools 模块中的函数让你可以执行很多迭代器操作，这些操作通常需要多行函数和复杂的列表理解。关于 Itertools 的神奇之处，请看以下示例：
from itertools import *
# Easy joining of two lists into a list of tuples
for i in izip([1, 2, 3], [ a , b , c ]):
print i
# ( a , 1)
# ( b , 2)
# ( c , 3)
# The count() function returns an interator that
# produces consecutive integers, forever. This
# one is great for adding indices next to your list
# elements for readability and convenience
for i in izip(count(1), [ Bob , Emily , Joe ]):
print i
# (1, Bob )
# (2, Emily )
# (3, Joe )
# The dropwhile() function returns an iterator that returns
# all the elements of the input which come after a certain
# condition becomes false for the first time.
def check_for_drop(x):
print Checking: , x
return (x > 5)
for i in dropwhile(should_drop, [2, 4, 6, 8, 10, 12]):
print Result: , i
# Checking: 2
# Checking: 4
# Result: 6
# Result: 8
# Result: 10
# Result: 12
# The groupby() function is great for retrieving bunches
# of iterator elements which are the same or have similar
# properties
a = sorted([1, 2, 1, 3, 2, 1, 2, 3, 4, 5])
for key, value in groupby(a):
print(key, value), end= )
# (1, [1, 1, 1])
# (2, [2, 2, 2])
# (3, [3, 3])
# (4, [4])
# (5, [5])
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