python学习（13）- 三大式

素颜马尾好姑娘i 2022-12-28 09:14 47阅读 0赞

Python学习（12）- 模块与包

[https://blog.csdn.net/caoyan0829/article/details/111209604][https_blog.csdn.net_caoyan0829_article_details_111209604]

三大式：

1.列表推导式

#简化代码，但是阅读性更复杂，不宜维护
    
    """
    1
    """
    l = []
    for i in range(10):
        l.append(i)
    print(l)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    
    # 列表推导式
    l1 = [i for i in range(10)]
    print(l1)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    
    """
    2
    """
    l3 = []
    for i in range(10):
        if i % 2 == 0:
            l3.append(i)
    print(l3) #[0, 2, 4, 6, 8]
    
    # 列表推导式
    l4 = [i for i in range(10) if i % 2 ==0]
    print(l4) #[0, 2, 4, 6, 8]
    
    """
    3
    """
    l5 = [i for i in range(5)  for j in range(3)]
    print(l5) #[0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4]
    
    l6 = []
    for i in range(5):
        for j in range(3):
            l6.append(i)
    print(l6) #[0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4]
    
    
    """
    4 双参数
    """
    l5 = [(i,j) for i in range(5)  for j in range(3)]
    print(l5)
    #[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2), (3, 0), (3, 1), (3, 2), (4, 0), (4, 1), (4, 2)]
    l6 = []
    for i in range(5):
        for j in range(3):
            l6.append((i,j))
    
    print(l6)
    #[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2), (3, 0), (3, 1), (3, 2), (4, 0), (4, 1), (4, 2)]

2.字典推导式

"""
    1
    """
    l = [0, 3, 31, 314, 54, 7, 854]
    import random
    
    # random.choice(l) 在l中 随机取值
    d = {k: random.choice(l) for k in range(5)}
    print(d)
    
    """
    2
    """
    d1 = {"a": 1, "b": 2, "c": 3}
    # d2 = {1: "a", 2: "b", 3: "c"}
    print(d1.values())
    d2 = {k: v for v, k in d1.items()}
    print(d2)  # {1: 'a', 2: 'b', 3: 'c'}
    
    # d2 = {}
    # for k,v in d1.items():
    #     print(k,v)
    #     d2[v] = k
    # print(d2)

3.集合推导式

s = {i for i in range(10)}
    print(s)

Python学习（14）- 生成器

[https://blog.csdn.net/caoyan0829/article/details/111292662][https_blog.csdn.net_caoyan0829_article_details_111292662]

[https_blog.csdn.net_caoyan0829_article_details_111209604]: https://blog.csdn.net/caoyan0829/article/details/111209604
[https_blog.csdn.net_caoyan0829_article_details_111292662]: https://blog.csdn.net/caoyan0829/article/details/111292662