python基础入门之十二 —— lambda表达式

def func0():
    return 100
func = lambda: 100  # lambda本质是一个匿名函数
print(func0)  # <function func0 at 0x000001F7FE355160>
print(func)  # <function <lambda> at 0x000001E20BAD5160>
print(func0())  # 100
print(func())  # 100

# 无参数
f1=lambda:100
print(f1()) # 100

# 一个参数
f2=lambda a:a
print(f2(‘Hello!‘))  # Hello！

# 默认参数
f3=lambda a,b,c=300:a+b+c
print(f3(100,200))  # 600

# 可变参数*args,返回元组
f4=lambda *args:args
print(f4(100,200,300))  # (100, 200, 300)

# 可变参数**kwargs，返回字典
f5=lambda **kwargs:kwargs
print(f5(name=‘Tom‘,age=10))  # {‘name‘: ‘Tom‘, ‘age‘: 10}

# 1、判断
func1 = lambda a,b: a if a>b else b
print(func1(2,3))  # 3
# 2、按照字典key排序
students = [
    {‘name‘:‘Alice‘,‘age‘:18},
    {‘name‘:‘Bill‘,‘age‘:20},
    {‘name‘:‘Cindy‘,‘age‘:16}
]
# 2.1、按照age升序排序
students.sort(key=lambda x:x[‘age‘])
print(students)  # [{‘name‘: ‘Cindy‘, ‘age‘: 16}, {‘name‘: ‘Alice‘, ‘age‘: 18}, {‘name‘: ‘Bill‘, ‘age‘: 20}]
# 2.2、按照name降序排序
students.sort(key=lambda x:x[‘name‘],reverse=True)
print(students)  # [{‘name‘: ‘Cindy‘, ‘age‘: 16}, {‘name‘: ‘Bill‘, ‘age‘: 20}, {‘name‘: ‘Alice‘, ‘age‘: 18}]