Python序列元素解壓全面介紹

p =(4

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

輸出： 4 5

data =[,

100,
4.5,
(2021,1
,28)]
name,weight,price,date = data
print
(name,weight,price,date)

name,weight,price,

(year,month,day)
= data
print
(name,weight,price,year,month,day)

**注意：**當變數個數與序列元素數量不匹配時，將出錯

a,b,c =

'abc'
print
(a,b,c)

輸出：a b c

name,_,price,_ = data

print
(name,price)

record =

['jenson'
,'[email protected]'
,'+86-020-12345678'
,'+86-13700000001'
]name,email,
*phones = record
print
(name,email,phones)

輸出：jenson [email protected] ['+86-020-12345678', '+86-13700000001']

*head,tail =[1

,2,3
,4,5
,6,7
,8,9
,0]print
(tail)
first,
*last =[1
,2,2
,3,4
,5,6
]print
(first)

輸出：

01

fruits =[(

,4.5),
('pear'
,3.8),
('banana'
,2.5),
('grape'
,12.3)]
for name,
*args in fruits:
if name ==
:print
(,args)

data =[,

100,
4.5,
(2021,1
,28)]
name,
*args,
(year,_,_)
= data
print
(name,year)

def

sum(values)
:    head,
*tail = values
return head +
sum(tail)
if tail else head

value =

sum([1
,2,3
,4,5
,6,7
,8,9
,0])
print
(value)

輸出45

from collections import deque

defkeep_last_n_elem
(values,pattern,history=5)
:        previous = deque(maxlen=history)
for value in values:
if value in pattern:
yield value,previous
with
open
('datas/somefile.txt'
)as f:
for line,prev in keep_last_n_elem(f,
'python'):
print
(len
(prev)
)for pline in prev:
print
(pline,end='')
print
(line,end='')
print
('-'*20
)

import heapq

nums =[1
,8,2
,23,7
,-4,
18,23,
42,37,
2]print
(heapq.nlargest(
3, nums)
)print
(heapq.nsmallest(
3, nums)
)

輸出：

[42, 37, 23]
[-4, 1, 2]

portfolio =[,

,,,,
]    cheap = heapq.nsmallest(
3, portfolio, key=
lambda s: s[
'price'])
print
(cheap)
expensive = heapq.nlargest(
3, portfolio, key=
lambda s: s[
'price'])
print
(expensive)

輸出：[, , ]

[, , ]

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