Python教程之无限迭代器的使用详解

# 演示迭代器模块的Python程序


import operator
import time

# 定义列表
L1 = [1, 2, 3]
L2 = [2, 3, 4]

# 映射函数之前的开始时间
t1 = time.time()

# 计算结果
a, b, c = map(operator.mul, L1, L2)

# 映射函数后的结束时间
t2 = time.time()

# 映射函数花费的时间
print("Result:", a, b, c)
print("Time taken by map function: %.6f" %(t2 - t1))

# 初始方法之前的开始时间
t1 = time.time()

# 使用for循环计算结果
print("Result:", end = " ")
for i in range(3):
	print(L1[i] * L2[i], end = " ")
	
# 朴素方法后的结束时间
t2 = time.time()
print("\nTime taken by for loop: %.6f" %(t2 - t1))

# 演示无限迭代器的Python程序

import itertools

# for 循环
for i in itertools.count(5, 5):
	if i == 35:
		break
	else:
		print(i, end =" ")

# 演示无限迭代器的Python程序

import itertools

count = 0

# for 循环
for i in itertools.cycle('AB'):
	if count > 7:
		break
	else:
		print(i, end = " ")
		count += 1

# 演示无限迭代器的Python程序

import itertools

l = ['Geeks', 'for', 'Geeks']

# 定义迭代器
iterators = itertools.cycle(l)

# for 循环
for i in range(6):
	
	# Using next function
	print(next(iterators), end = " ")

# 演示 repeat() 工作的Python代码
	
# 为迭代器操作导入“itertools”
import itertools
	
# 使用 repeat() 重复打印数字
print ("Printing the numbers repeatedly : ")
print (list(itertools.repeat(25, 4)))