????? 4. ??????????? ????? Python ??? ??? 6. ???

????

• 5.1 ????????

  • 5.1.1 ???????????????

  • 5.1.2 ????????????????

  • 5.1.3 ????????????

  • 5.1.4 ????????

• 5.2 del ???

• 5.3 ??饗Tuples?? ?? ???У?Sequences??

• 5.4 ???Dictionaries??

• 5.5 ???????

• 5.6 ????????????

• 5.7 ??????У?Sequences????????????

 
5. ?????

????????????Щ????????????????????????????μ??????

 
5.1 ????????

?????????к????????????????????????з?????

??????????????????β?????? a[len(a):] = [x]??

???????????????????????????????????? a[len(a):] = L ??

?????λ?ò??????????????????????????????????????????????????? a.insert(0, x) ??????????????????? a.insert(len(a), x) ???? a.append(x)??

???????????x??????????????????????????????????????

??????????λ?????????????????????????????????a.pop() ??????????????????漴???????б??????????????i?????????????????????????????????????????????????????????Python ??ο?????????????????????

?????????е??????x????????????????????????????????????

????x???????г?????????

???????е????????????????

?????????е?????

????????????????????????????

>>> a = [66.6, 333, 333, 1, 1234.5]
>>> print a.count(333), a.count(66.6), a.count('x')
2 1 0
>>> a.insert(2, -1)
>>> a.append(333)
>>> a
[66.6, 333, -1, 333, 1, 1234.5, 333]
>>> a.index(333)
1
>>> a.remove(333)
>>> a
[66.6, -1, 333, 1, 1234.5, 333]
>>> a.reverse()
>>> a
[333, 1234.5, 1, 333, -1, 66.6]
>>> a.sort()
>>> a
[-1, 1, 66.6, 333, 333, 1234.5]

 
5.1.1 ???????????????

?????????????????????????????????????????????????????????????????????????????????????????? append() ???????????????????????????ò?????????? pop() ???????????????????????????????磺

>>> stack = [3, 4, 5]
>>> stack.append(6)
>>> stack.append(7)
>>> stack
[3, 4, 5, 6, 7]
>>> stack.pop()
7
>>> stack
[3, 4, 5, 6]
>>> stack.pop()
6
>>> stack.pop()
5
>>> stack
[3, 4]

 
5.1.2 ????????????????

?????????????????????????????????????????????????????????????????????????? append()?????????????????????????0????????? pop() ???????????????????????????????磺

>>> queue = ["Eric", "John", "Michael"]
>>> queue.append("Terry")           # Terry arrives
>>> queue.append("Graham")          # Graham arrives
>>> queue.pop(0)
'Eric'
>>> queue.pop(0)
'John'
>>> queue
['Michael', 'Terry', 'Graham']

 
5.1.3 ????????????

???????????????????????ú???????????filter()?? map()?? ?? reduce()??

“filter(function, sequence)” ??????????У?sequence??????????????????????е???function(item)??????true??????????????????????????????????????磬???3?????????????????

>>> def f(x): return x % 2 != 0 and x % 3 != 0
...
>>> filter(f, range(2, 25))
[5, 7, 11, 13, 17, 19, 23]

“map(function, sequence)” ???????????ε??? function(item) ??????????????????????????磬???3????????????

>>> def cube(x): return x*x*x
...
>>> map(cube, range(1, 11))
[1, 8, 27, 64, 125, 216, 343, 512, 729, 1000]

????????????У????????????ж????????????????????????????????????????????ú?????????Щ???б?????????????None?????棩???????None?????????????????????????????????

?????????????????????“map(None, list1, list2)”?????????б?????????е??????????磺

>>> seq = range(8)
>>> def square(x): return x*x
...
>>> map(None, seq, map(square, seq))
[(0, 0), (1, 1), (2, 4), (3, 9), (4, 16), (5, 25), (6, 36), (7, 49)]

"reduce(func, sequence)" ???????????????????????????????????е???????????ú????????????????????????????????????????????磬???3??????1??10??????????

>>> def add(x,y): return x+y
...
>>> reduce(add, range(1, 11))
55

????????????????????????????????????????????????????

????????????????????????????????????????????????????????????????????е?????????????????????????????????????????磺

>>> def sum(seq):
...     def add(x,y): return x+y
...     return reduce(add, seq, 0)
... 
>>> sum(range(1, 11))
55
>>> sum([])
0

?????????????????? sum()???????????????????????????μ?2.3???У?????????? sum(sequence) ??????

5.1.4 ????????

????????????????????????????????????? map()?? filter() ??? lambda?? ???????????????????????Щ????????????????????????????????for?????????????????for??if????????????for??if?????????????????????????????????????????飬??????????????

>>> freshfruit = ['  banana', '  loganberry ', 'passion fruit  ']
>>> [weapon.strip() for weapon in freshfruit]
['banana', 'loganberry', 'passion fruit']
>>> vec = [2, 4, 6]
>>> [3*x for x in vec]
[6, 12, 18]
>>> [3*x for x in vec if x > 3]
[12, 18]
>>> [3*x for x in vec if x < 2]
[]
>>> [[x,x**2] for x in vec]
[[2, 4], [4, 16], [6, 36]]
>>> [x, x**2 for x in vec]      # error - parens required for tuples
  File "<stdin>", line 1, in ?
    [x, x**2 for x in vec]
               ^
SyntaxError: invalid syntax
>>> [(x, x**2) for x in vec]
[(2, 4), (4, 16), (6, 36)]
>>> vec1 = [2, 4, 6]
>>> vec2 = [4, 3, -9]
>>> [x*y for x in vec1 for y in vec2]
[8, 6, -18, 16, 12, -36, 24, 18, -54]
>>> [x+y for x in vec1 for y in vec2]
[6, 5, -7, 8, 7, -5, 10, 9, -3]
>>> [vec1[i]*vec2[i] for i in range(len(vec1))]
[8, 12, -54]

?????????????for?????????????????????????????????

>>> x = 100                     # this gets overwritten
>>> [x**3 for x in range(5)]
[0, 1, 8, 27, 64]
>>> x                           # the final value for range(5)
4

 
5.2 del ???

??????????????????????????????????del?????????????????????????????????????????????????????????????磺

>>> a = [-1, 1, 66.6, 333, 333, 1234.5]
>>> del a[0]
>>> a
[1, 66.6, 333, 333, 1234.5]
>>> del a[2:4]
>>> a
[1, 66.6, 1234.5]

del ??????????????????????

>>> del a

?????????????????????????????????????????????????????????????del???????÷???

 
5.3 ??饗Tuples?? ?????У?Sequences ??

??????????????????к?????????????????????????????????????????????е?????????Python???????????????????????????????????????????????????????????????????顣

???????????????????????????磺

>>> t = 12345, 54321, 'hello!'
>>> t[0]
12345
>>> t
(12345, 54321, 'hello!')
>>> # Tuples may be nested:
... u = t, (1, 2, 3, 4, 5)
>>> u
((12345, 54321, 'hello!'), (1, 2, 3, 4, 5))

????????????????????????????????????????????????????????????л???????????????????????????????????????????????????????????????

????к??????????磨x, y?????????????е???????????????????????????????????????????????????????????????????????????????￡?????????????????????????????飬?????????

??????????????????????????????????飺??????????????????????Щ??????????????????????????飻??????????????????????????????????????????з?????????????????????a????????Ч?????磺

>>> empty = ()
>>> singleton = 'hello',    # <-- note trailing comma
>>> len(empty)
0
>>> len(singleton)
1
>>> singleton
('hello',)

??? t = 12345, 54321, 'hello!' ?????????sequence packing????????????? 12345?? 54321 ?? 'hello!' ?????????顣???????????????????

>>> x, y, z = t

??????????????в?????????????в????????????????????е??????????????????????????multiple assignment

??????????????????в??????????

???????????????????????????????????飬???????????????????κ????С?

 
5.4 ???Dictionaries??

?????????????Python????????????????Dictionaries??????????Щ?????п?????“???????”??``associative memories''????“????????”??``associative arrays''????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? append() ?? extend() ????????????????????????????????????????

???????????????????????????????????? key:value pairs ?????????????????????????????????????????????????????????????{}????????????????????????????鶺???????????????????????????????

????????????????????????洢???????????????del?????????????????????????????????????洢????????ù?????????????????????????????????????????ж??????′???

????keys() ?????????????й??????????????????????????????????????????????ù?????????sort()??????????????? has_key() ?????????????????????????????

??????????????????С?????

>>> tel = {'jack': 4098, 'sape': 4139}
>>> tel['guido'] = 4127
>>> tel
{'sape': 4139, 'guido': 4127, 'jack': 4098}
>>> tel['jack']
4098
>>> del tel['sape']
>>> tel['irv'] = 4127
>>> tel
{'guido': 4127, 'irv': 4127, 'jack': 4098}
>>> tel.keys()
['guido', 'irv', 'jack']
>>> tel.has_key('guido')
True

?????д洢?????-??????????????????????????????-???????????????????????????????????????-??????

>>> dict([('sape', 4139), ('guido', 4127), ('jack', 4098)])
{'sape': 4139, 'jack': 4098, 'guido': 4127}
>>> dict([(x, x**2) for x in vec])     # use a list comprehension
{2: 4, 4: 16, 6: 36}

 
5.5 ???????

??????????????????????????????? items() ???????????????

>>> knights = {'gallahad': 'the pure', 'robin': 'the brave'}
>>> for k, v in knights.items():
...     print k, v
...
gallahad the pure
robin the brave

??????????????????λ?ú??????????? enumerate() ???????????

 
>>> for i, v in enumerate(['tic', 'tac', 'toe']):
...     print i, v
...
0 tic
1 tac
2 toe

??????????????????У???????? zip() ????????

>>> questions = ['name', 'quest', 'favorite color']
>>> answers = ['lancelot', 'the holy grail', 'blue']
>>> for q, a in zip(questions, answers):
...     print 'What is your %s?  It is %s.' % (q, a)
...     
What is your name?  It is lancelot.
What is your quest?  It is the holy grail.
What is your favorite color?  It is blue.

 
5.6 ????????????

????while??if???????????????????????????

in??not??????????????????????????????????is??is not??????????????????? ?????????????????????????й?????е???????????????????????????????е??????????

?????????????????? a < b == c ??????aС??b??b????c??

??????????????????????and??or????????????????not??????塣??Щ???????????????????????????????????У?not???????????????or????????????????A and not B or C ???? (A and (not B)) or C??????????????????????????????

?????????and ??or ???????·???????????????????????????????????????????????????磬???A??C????B????A and B and C ???????C??????????????????????????·?????????????????????????????

?????????????????????????????????????????磺

>>> string1, string2, string3 = '', 'Trondheim', 'Hammer Dance'
>>> non_null = string1 or string2 or string3
>>> non_null
'Trondheim'

?????????Python??C??????????????????????C ?????????????????????????????????C????????????????????????????==????????????????

 
5.7 ??????к?????????

???ж??????????????????????????? ???????????????У??????????????????????????????????????????????????????????????????????????????ж??????????????????????????????????У???????????????????????е??????????????????????????????????????????????е????????У???????????о?С?????????????????????????????ASCII?????????????????????????Щ?????

(1, 2, 3)              < (1, 2, 4)
[1, 2, 3]              < [1, 2, 4]
'ABC' < 'C' < 'Pascal' < 'Python'
(1, 2, 3, 4)           < (1, 2, 4)
(1, 2)                 < (1, 2, -1)
(1, 2, 3)             == (1.0, 2.0, 3.0)
(1, 2, ('aa', 'ab'))   < (1, 2, ('abc', 'a'), 4)

????????????????????????????????????????????????????????????????????????????????list??????С????????????string??????????????string??????С???????饗tuple??????????????????????????????????????0????0.0??????^5.1

???

... etc.^5.1

?????????????????????????????п??????Python???????汾?и??

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????? 4. ??????????? ????? Python ??? ??? 6. ???

Release 2.3, documentation updated on July 29, 2003.