所谓的解包（Unpacking）实际上可以看做是去掉()的元组或者是去掉{}的字典。

解包sequence

p = (4,5)
x,y = p
print(x)
print(y)
#x=4
#y=5

data = ["Alice",50,91.1,(2012,12,21)]
name,shares,price,date = data
print(name)
print(date)

#"Alice"
#(2012,12,21)

name,shares,price,(year,mon,day) = data

print(name)

print(year)

print(mon)

print(day)



#Alice

#2012

#12

#21

解包string

s = "Hello"
a,b,c,d,e = s
print("a=",a,"b=",b,"c=",c,"d=",d,"e=",e)
# a= H b= e c= l d= l e= o

解包指定定内容

data = ["ACME",50,91.1,(2012,12,21)]

_,share,price,_ = data

print(share)

print(price)

# 50

# 91.1

前后任意长度解包

中间

def drop_first_last(grades):

    first,*middle,last = grades

    # return "".join(middle)

    return middle

print(drop_first_last("afafasfdsfa"))

# fafasfdsf

#不加"".join(middle),会返回一个列表['f', 'a', 'f', 'a', 's', 'f', 'd', 's', 'f']

最后

record = ("Dave","[email protected]","773-555-1212","847-555-1212")

name,email,*phone_numbers = record

print(name)

print(email)

print(phone_numbers)

# Dave

# [email protected]

# ['773-555-1212', '847-555-1212']

第一个

*trailing, current = [10, 8, 7, 1, 9, 5, 10, 3]
print(trailing)
print(current)
# [10, 8, 7, 1, 9, 5, 10]
# 3

解包包含tag的元组

records = [("foo",1,2),("bar","hello"),("foo",3,4)]
def do_foo(x,y):
    print("foo",x,y)
def do_bar(s):
    print("bar",s)
for tag,*args in records:
    if tag == "foo":
        do_foo(*args)
    elif tag == "bar":
        do_bar(*args)

# foo 1 2
# bar hello
# foo 3 4

解包实际应用

line = "nobody:*:-2:-2:Unprivileged User:/var/empty:/usr/bin/false"

uname,*field,homedir,sh = line.split(":")

print(uname)

print(homedir)

print(sh)



# nobody

# /var/empty

# /usr/bin/false

数组里面有元组的情况

record = ("ACME",50,123.45,(12,18,2012))

name,*_,(*_,year) = record

print(name)

print(year)



# ACME

# 2012