Python itertools库高效迭代艺术实例探索

from itertools import count, cycle, repeat

# 生成自然数序列
natural_numbers = count(start=1, step=1)

# 重复迭代一个序列
repeated_sequence = cycle([1, 2, 3])

# 重复迭代一个元素
repeated_element = repeat(5, times=3)

from itertools import permutations, combinations

# 生成元素的所有排列
perms = permutations('ABC', r=2)

# 生成元素的所有组合
combs = combinations('XYZ', r=2)

from itertools import zip_longest, chain

# 处理可变长度的迭代对象
zipped = zip_longest('ABC', '123', fillvalue='NA')

# 将多个迭代器连接起来
merged = chain([1, 2, 3], ['a', 'b', 'c'])

from itertools import takewhile, dropwhile

# 根据条件获取元素
filtered_items = takewhile(lambda x: x < 5, [1, 3, 7, 2, 4])

# 根据条件跳过元素
skipped_items = dropwhile(lambda x: x < 5, [1, 3, 7, 2, 4])

from itertools import product, zip

# 生成多个可迭代对象的笛卡尔积
cartesian_product = product([1, 2], ['a', 'b'])

# 将多个迭代器的元素配对
paired_items = zip([1, 2, 3], ['a', 'b', 'c'])

from itertools import compress, accumulate

# 根据布尔序列压缩迭代器
compressed_items = compress('ABC', [True, False, True])

# 对迭代器进行累积操作
accumulated_values = accumulate([1, 2, 3, 4])

from itertools import tee

# 自定义迭代器生成斐波那契数列
def fibonacci():
    a, b = 0, 1
    while True:
        yield a
        a, b = b, a + b

# 使用 tee 方法复制迭代器
fibonacci_iter1, fibonacci_iter2 = tee(fibonacci())