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函数 Function

def get_choices():
    player_input = input("input:")
    player_choice_internal = "rock"
    return player_input

Parameter and return​

def get_win(player, computer):
    return [player, computer]
def hello():
    return "name", 8

print(hello()) # ("name", 8)

Variable Scope​

age = 8
def test():
    print(age)

print(page) # 8
test() # 8

Nested Fucntions​

def talk(phrase):
    def say(word):
        print(word)

    words = phrase.split(" ")
    for word in words:
        say(word)
talk("I am going to buy the milk")
Error without 'nonlocal'
def count1():
    count = 0

    def increment():
        nonlocal count # 嵌入式函数中的无法访问外层的变量
        count += 1
        print(count)
    increment()
count1()
count_v = 0

def count2():
    print(count_v) # count_v 是全局变量，所以可访问到
count2()
Error without 'global'
count_v = 0

def count2():
    global count_v # 需要标明此变量是全局变量
    count_v += 1 # 无法仅凭借这行修改，因为无法找到本地变量，也不知道 count_v 是全局变量
    print(count_v)
count2()

Closure​

def counter():
    count = 0

    def increment():
        nonlocal count # 嵌入式函数中的无法访问外层的变量
        count += 1
        print(count)

    return increment
increment = counter()
increment() # 1
increment() # 2
increment() # 3

Lambda Functions​

lambda num : num * 2
multiply = lambda a, b : a * b
multiply(2, 4) # 8

*args and **kwargs​

  • *args: Non-Keyword Arguments
  • **kwargs: Keyword Arguments

*args​

def myFun(*argv):
    for arg in argv:
        print(arg)

myFun('Hello', 'Welcome', 'to', 'GeeksforGeeks')
# Hello
# Welcome
# to
# GeeksforGeeks
def myFun(arg1, *argv):
    print("First argument :", arg1)
    for arg in argv:
        print("Next argument through *argv :", arg)

myFun('Hello', 'Welcome', 'to', 'GeeksforGeeks')
# First argument : Hello
# Next argument through *argv : Welcome
# Next argument through *argv : to
# Next argument through *argv : GeeksforGeeks

**kwargs​

def myFun(**kwargs):
    for key, value in kwargs.items():
        print("%s == %s" % (key, value))

myFun(first='Geeks', mid='for', last='Geeks')
# first == Geeks
# mid == for
# last == Geeks
def myFun(arg1, **kwargs):
    for key, value in kwargs.items():
        print("%s == %s" % (key, value))

# Driver code
myFun("Hi", first='Geeks', mid='for', last='Geeks')
# first == Geeks
# mid == for
# last == Geeks

Using both *args and **kwargs in Python to call a function​


def myFun(arg1, arg2, arg3):
    print("arg1:", arg1)
    print("arg2:", arg2)
    print("arg3:", arg3)


# Now we can use *args or **kwargs to
# pass arguments to this function :
args = ("Geeks", "for", "Geeks")
myFun(*args)

kwargs = {"arg1": "Geeks", "arg2": "for", "arg3": "Geeks"}
myFun(**kwargs)
def myFun(*args, **kwargs):
    print("args: ", args)
    print("kwargs: ", kwargs)

# Now we can use both *args ,**kwargs
# to pass arguments to this function :
myFun('geeks', 'for', 'geeks', first="Geeks", mid="for", last="Geeks")