迭代器操作函数的使用

笔记

lst = [54, 56, 77, 4, 567, 34]
# (1)排序操作
asc_lst = sorted(lst)  # 升序
desc_lst = sorted(lst, reverse=True)  # 降序
print('原列表：', lst)
print('升序：', asc_lst)
print('降序：', desc_lst)

# (2)reversed 反向
new_lst = reversed(lst)
print(type(new_lst))  # <class 'list_reverseiterator'> 迭代器对象
print(list(new_lst))

# (3)zip
x = ['a', 'b', 'c', 'd']
y = [10, 20, 30, 40, 50]
zipobj = zip(x, y)
print(type(zipobj))  # <class 'zip'>
# print(list(zipobj))

# enumerate
enum = enumerate(y, start=1)
print(type(enum))  # <class 'enumerate'>
print(tuple(enum))

# (5)all
lst2 = [10, 20, '', 30]
print(all(lst2))  # False,空字符串的布尔值是False
print(all(lst))  # True

# (6)any
print(any(lst2))  # True

# (7)
print(next(zipobj))  # ('a', 10)
print(next(zipobj))
print(next(zipobj))


def fun(num):
    return num % 2 == 1  # 可能是True,False


obj = filter(fun, range(10))  # 将range(10),0-9的整数，都执行一次fun操作
print(list(obj))  # [1, 3, 5, 7, 9]

def upper(x):
    return x.upper()

new_lst2=['hello','world','python']
obj2=map(upper,new_lst2)
print(list(obj2))