python的基础类源码解析——collection类

1、计数器(counter)

Counter是对字典类型的补充,用于追踪值的出现次数。

ps:具备字典的所有功能 + 自己的功能

  1 ########################################################################
  2 ###  Counter
  3 ########################################################################
  4 
  5 class Counter(dict):
  6     '''Dict subclass for counting hashable items.  Sometimes called a bag
  7     or multiset.  Elements are stored as dictionary keys and their counts
  8     are stored as dictionary values.
  9 
 10     >>> c = Counter('abcdeabcdabcaba')  # count elements from a string
 11 
 12     >>> c.most_common(3)                # three most common elements
 13     [('a', 5), ('b', 4), ('c', 3)]
 14     >>> sorted(c)                       # list all unique elements
 15     ['a', 'b', 'c', 'd', 'e']
 16     >>> ''.join(sorted(c.elements()))   # list elements with repetitions
 17     'aaaaabbbbcccdde'
 18     >>> sum(c.values())                 # total of all counts
 19 
 20     >>> c['a']                          # count of letter 'a'
 21     >>> for elem in 'shazam':           # update counts from an iterable
 22     ...     c[elem] += 1                # by adding 1 to each element's count
 23     >>> c['a']                          # now there are seven 'a'
 24     >>> del c['b']                      # remove all 'b'
 25     >>> c['b']                          # now there are zero 'b'
 26 
 27     >>> d = Counter('simsalabim')       # make another counter
 28     >>> c.update(d)                     # add in the second counter
 29     >>> c['a']                          # now there are nine 'a'
 30 
 31     >>> c.clear()                       # empty the counter
 32     >>> c
 33     Counter()
 34 
 35     Note:  If a count is set to zero or reduced to zero, it will remain
 36     in the counter until the entry is deleted or the counter is cleared:
 37 
 38     >>> c = Counter('aaabbc')
 39     >>> c['b'] -= 2                     # reduce the count of 'b' by two
 40     >>> c.most_common()                 # 'b' is still in, but its count is zero
 41     [('a', 3), ('c', 1), ('b', 0)]
 42 
 43     '''
 44     # References:
 45     #   http://en.wikipedia.org/wiki/Multiset
 46     #   http://www.gnu.org/software/smalltalk/manual-base/html_node/Bag.html
 47     #   http://www.demo2s.com/Tutorial/Cpp/0380__set-multiset/Catalog0380__set-multiset.htm
 48     #   http://code.activestate.com/recipes/259174/
 49     #   Knuth, TAOCP Vol. II section 4.6.3
 50 
 51     def __init__(self, iterable=None, **kwds):
 52         '''Create a new, empty Counter object.  And if given, count elements
 53         from an input iterable.  Or, initialize the count from another mapping
 54         of elements to their counts.
 55 
 56         >>> c = Counter()                           # a new, empty counter
 57         >>> c = Counter('gallahad')                 # a new counter from an iterable
 58         >>> c = Counter({'a': 4, 'b': 2})           # a new counter from a mapping
 59         >>> c = Counter(a=4, b=2)                   # a new counter from keyword args
 60 
 61         '''
 62         super(Counter, self).__init__()
 63         self.update(iterable, **kwds)
 64 
 65     def __missing__(self, key):
 66         """ 对于不存在的元素,返回计数器为0 """
 67         'The count of elements not in the Counter is zero.'
 68         # Needed so that self[missing_item] does not raise KeyError
 69         return 0
 70 
 71     def most_common(self, n=None):
 72         """ 数量大于等n的所有元素和计数器 """
 73         '''List the n most common elements and their counts from the most
 74         common to the least.  If n is None, then list all element counts.
 75 
 76         >>> Counter('abcdeabcdabcaba').most_common(3)
 77         [('a', 5), ('b', 4), ('c', 3)]
 78 
 79         '''
 80         # Emulate Bag.sortedByCount from Smalltalk
 81         if n is None:
 82             return sorted(self.iteritems(), key=_itemgetter(1), reverse=True)
 83         return _heapq.nlargest(n, self.iteritems(), key=_itemgetter(1))
 84 
 85     def elements(self):
 86         """ 计数器中的所有元素,注:此处非所有元素集合,而是包含所有元素集合的迭代器 """
 87         '''Iterator over elements repeating each as many times as its count.
 88 
 89         >>> c = Counter('ABCABC')
 90         >>> sorted(c.elements())
 91         ['A', 'A', 'B', 'B', 'C', 'C']
 92 
 93         # Knuth's example for prime factors of 1836:  2**2 * 3**3 * 17**1
 94         >>> prime_factors = Counter({2: 2, 3: 3, 17: 1})
 95         >>> product = 1
 96         >>> for factor in prime_factors.elements():     # loop over factors
 97         ...     product *= factor                       # and multiply them
 98         >>> product
 99 
100         Note, if an element's count has been set to zero or is a negative
101         number, elements() will ignore it.
102 
103         '''
104         # Emulate Bag.do from Smalltalk and Multiset.begin from C++.
105         return _chain.from_iterable(_starmap(_repeat, self.iteritems()))
106 
107     # Override dict methods where necessary
108 
109     @classmethod
110     def fromkeys(cls, iterable, v=None):
111         # There is no equivalent method for counters because setting v=1
112         # means that no element can have a count greater than one.
113         raise NotImplementedError(
114             'Counter.fromkeys() is undefined.  Use Counter(iterable) instead.')
115 
116     def update(self, iterable=None, **kwds):
117         """ 更新计数器,其实就是增加;如果原来没有,则新建,如果有则加一 """
118         '''Like dict.update() but add counts instead of replacing them.
119 
120         Source can be an iterable, a dictionary, or another Counter instance.
121 
122         >>> c = Counter('which')
123         >>> c.update('witch')           # add elements from another iterable
124         >>> d = Counter('watch')
125         >>> c.update(d)                 # add elements from another counter
126         >>> c['h']                      # four 'h' in which, witch, and watch
127 
128         '''
129         # The regular dict.update() operation makes no sense here because the
130         # replace behavior results in the some of original untouched counts
131         # being mixed-in with all of the other counts for a mismash that
132         # doesn't have a straight-forward interpretation in most counting
133         # contexts.  Instead, we implement straight-addition.  Both the inputs
134         # and outputs are allowed to contain zero and negative counts.
135 
136         if iterable is not None:
137             if isinstance(iterable, Mapping):
138                 if self:
139                     self_get = self.get
140                     for elem, count in iterable.iteritems():
141                         self[elem] = self_get(elem, 0) + count
142                 else:
143                     super(Counter, self).update(iterable) # fast path when counter is empty
144             else:
145                 self_get = self.get
146                 for elem in iterable:
147                     self[elem] = self_get(elem, 0) + 1
148         if kwds:
149             self.update(kwds)
150 
151     def subtract(self, iterable=None, **kwds):
152         """ 相减,原来的计数器中的每一个元素的数量减去后添加的元素的数量 """
153         '''Like dict.update() but subtracts counts instead of replacing them.
154         Counts can be reduced below zero.  Both the inputs and outputs are
155         allowed to contain zero and negative counts.
156 
157         Source can be an iterable, a dictionary, or another Counter instance.
158 
159         >>> c = Counter('which')
160         >>> c.subtract('witch')             # subtract elements from another iterable
161         >>> c.subtract(Counter('watch'))    # subtract elements from another counter
162         >>> c['h']                          # 2 in which, minus 1 in witch, minus 1 in watch
163         >>> c['w']                          # 1 in which, minus 1 in witch, minus 1 in watch
164         -1
165 
166         '''
167         if iterable is not None:
168             self_get = self.get
169             if isinstance(iterable, Mapping):
170                 for elem, count in iterable.items():
171                     self[elem] = self_get(elem, 0) - count
172             else:
173                 for elem in iterable:
174                     self[elem] = self_get(elem, 0) - 1
175         if kwds:
176             self.subtract(kwds)
177 
178     def copy(self):
179         """ 拷贝 """
180         'Return a shallow copy.'
181         return self.__class__(self)
182 
183     def __reduce__(self):
184         """ 返回一个元组(类型,元组) """
185         return self.__class__, (dict(self),)
186 
187     def __delitem__(self, elem):
188         """ 删除元素 """
189         'Like dict.__delitem__() but does not raise KeyError for missing values.'
190         if elem in self:
191             super(Counter, self).__delitem__(elem)
192 
193     def __repr__(self):
194         if not self:
195             return '%s()' % self.__class__.__name__
196         items = ', '.join(map('%r: %r'.__mod__, self.most_common()))
197         return '%s({%s})' % (self.__class__.__name__, items)
198 
199     # Multiset-style mathematical operations discussed in:
200     #       Knuth TAOCP Volume II section 4.6.3 exercise 19
201     #       and at http://en.wikipedia.org/wiki/Multiset
202     #
203     # Outputs guaranteed to only include positive counts.
204     #
205     # To strip negative and zero counts, add-in an empty counter:
206     #       c += Counter()
207 
208     def __add__(self, other):
209         '''Add counts from two counters.
210 
211         >>> Counter('abbb') + Counter('bcc')
212         Counter({'b': 4, 'c': 2, 'a': 1})
213 
214         '''
215         if not isinstance(other, Counter):
216             return NotImplemented
217         result = Counter()
218         for elem, count in self.items():
219             newcount = count + other[elem]
220             if newcount > 0:
221                 result[elem] = newcount
222         for elem, count in other.items():
223             if elem not in self and count > 0:
224                 result[elem] = count
225         return result
226 
227     def __sub__(self, other):
228         ''' Subtract count, but keep only results with positive counts.
229 
230         >>> Counter('abbbc') - Counter('bccd')
231         Counter({'b': 2, 'a': 1})
232 
233         '''
234         if not isinstance(other, Counter):
235             return NotImplemented
236         result = Counter()
237         for elem, count in self.items():
238             newcount = count - other[elem]
239             if newcount > 0:
240                 result[elem] = newcount
241         for elem, count in other.items():
242             if elem not in self and count < 0:
243                 result[elem] = 0 - count
244         return result
245 
246     def __or__(self, other):
247         '''Union is the maximum of value in either of the input counters.
248 
249         >>> Counter('abbb') | Counter('bcc')
250         Counter({'b': 3, 'c': 2, 'a': 1})
251 
252         '''
253         if not isinstance(other, Counter):
254             return NotImplemented
255         result = Counter()
256         for elem, count in self.items():
257             other_count = other[elem]
258             newcount = other_count if count < other_count else count
259             if newcount > 0:
260                 result[elem] = newcount
261         for elem, count in other.items():
262             if elem not in self and count > 0:
263                 result[elem] = count
264         return result
265 
266     def __and__(self, other):
267         ''' Intersection is the minimum of corresponding counts.
268 
269         >>> Counter('abbb') & Counter('bcc')
270         Counter({'b': 1})
271 
272         '''
273         if not isinstance(other, Counter):
274             return NotImplemented
275         result = Counter()
276         for elem, count in self.items():
277             other_count = other[elem]
278             newcount = count if count < other_count else other_count
279             if newcount > 0:
280                 result[elem] = newcount
281         return result
282 
283 Counter
Counter Code

我们从中挑选一些相对常用的方法来举例:

在上面的例子我们可以看出,counter方法返回的是一个字典,它将字符串中出现的所有字符都进行了统计。在这里再介绍一下update方法,这个update方法是将两次统计的结果相加,和字典的update略有不同。

  

2、有序字典(orderedDict )

orderdDict是对字典类型的补充,他记住了字典元素添加的顺序

  1 class OrderedDict(dict):
  2     'Dictionary that remembers insertion order'
  3     # An inherited dict maps keys to values.
  4     # The inherited dict provides __getitem__, __len__, __contains__, and get.
  5     # The remaining methods are order-aware.
  6     # Big-O running times for all methods are the same as regular dictionaries.
  7 
  8     # The internal self.__map dict maps keys to links in a doubly linked list.
  9     # The circular doubly linked list starts and ends with a sentinel element.
 10     # The sentinel element never gets deleted (this simplifies the algorithm).
 11     # Each link is stored as a list of length three:  [PREV, NEXT, KEY].
 12 
 13     def __init__(self, *args, **kwds):
 14         '''Initialize an ordered dictionary.  The signature is the same as
 15         regular dictionaries, but keyword arguments are not recommended because
 16         their insertion order is arbitrary.
 17 
 18         '''
 19         if len(args) > 1:
 20             raise TypeError('expected at most 1 arguments, got %d' % len(args))
 21         try:
 22             self.__root
 23         except AttributeError:
 24             self.__root = root = []                     # sentinel node
 25             root[:] = [root, root, None]
 26             self.__map = {}
 27         self.__update(*args, **kwds)
 28 
 29     def __setitem__(self, key, value, dict_setitem=dict.__setitem__):
 30         'od.__setitem__(i, y) <==> od[i]=y'
 31         # Setting a new item creates a new link at the end of the linked list,
 32         # and the inherited dictionary is updated with the new key/value pair.
 33         if key not in self:
 34             root = self.__root
 35             last = root[0]
 36             last[1] = root[0] = self.__map[key] = [last, root, key]
 37         return dict_setitem(self, key, value)
 38 
 39     def __delitem__(self, key, dict_delitem=dict.__delitem__):
 40         'od.__delitem__(y) <==> del od[y]'
 41         # Deleting an existing item uses self.__map to find the link which gets
 42         # removed by updating the links in the predecessor and successor nodes.
 43         dict_delitem(self, key)
 44         link_prev, link_next, _ = self.__map.pop(key)
 45         link_prev[1] = link_next                        # update link_prev[NEXT]
 46         link_next[0] = link_prev                        # update link_next[PREV]
 47 
 48     def __iter__(self):
 49         'od.__iter__() <==> iter(od)'
 50         # Traverse the linked list in order.
 51         root = self.__root
 52         curr = root[1]                                  # start at the first node
 53         while curr is not root:
 54             yield curr[2]                               # yield the curr[KEY]
 55             curr = curr[1]                              # move to next node
 56 
 57     def __reversed__(self):
 58         'od.__reversed__() <==> reversed(od)'
 59         # Traverse the linked list in reverse order.
 60         root = self.__root
 61         curr = root[0]                                  # start at the last node
 62         while curr is not root:
 63             yield curr[2]                               # yield the curr[KEY]
 64             curr = curr[0]                              # move to previous node
 65 
 66     def clear(self):
 67         'od.clear() -> None.  Remove all items from od.'
 68         root = self.__root
 69         root[:] = [root, root, None]
 70         self.__map.clear()
 71         dict.clear(self)
 72 
 73     # -- the following methods do not depend on the internal structure --
 74 
 75     def keys(self):
 76         'od.keys() -> list of keys in od'
 77         return list(self)
 78 
 79     def values(self):
 80         'od.values() -> list of values in od'
 81         return [self[key] for key in self]
 82 
 83     def items(self):
 84         'od.items() -> list of (key, value) pairs in od'
 85         return [(key, self[key]) for key in self]
 86 
 87     def iterkeys(self):
 88         'od.iterkeys() -> an iterator over the keys in od'
 89         return iter(self)
 90 
 91     def itervalues(self):
 92         'od.itervalues -> an iterator over the values in od'
 93         for k in self:
 94             yield self[k]
 95 
 96     def iteritems(self):
 97         'od.iteritems -> an iterator over the (key, value) pairs in od'
 98         for k in self:
 99             yield (k, self[k])
100 
101     update = MutableMapping.update
102 
103     __update = update # let subclasses override update without breaking __init__
104 
105     __marker = object()
106 
107     def pop(self, key, default=__marker):
108         '''od.pop(k[,d]) -> v, remove specified key and return the corresponding
109         value.  If key is not found, d is returned if given, otherwise KeyError
110         is raised.
111 
112         '''
113         if key in self:
114             result = self[key]
115             del self[key]
116             return result
117         if default is self.__marker:
118             raise KeyError(key)
119         return default
120 
121     def setdefault(self, key, default=None):
122         'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od'
123         if key in self:
124             return self[key]
125         self[key] = default
126         return default
127 
128     def popitem(self, last=True):
129         '''od.popitem() -> (k, v), return and remove a (key, value) pair.
130         Pairs are returned in LIFO order if last is true or FIFO order if false.
131 
132         '''
133         if not self:
134             raise KeyError('dictionary is empty')
135         key = next(reversed(self) if last else iter(self))
136         value = self.pop(key)
137         return key, value
138 
139     def __repr__(self, _repr_running={}):
140         'od.__repr__() <==> repr(od)'
141         call_key = id(self), _get_ident()
142         if call_key in _repr_running:
143             return '...'
144         _repr_running[call_key] = 1
145         try:
146             if not self:
147                 return '%s()' % (self.__class__.__name__,)
148             return '%s(%r)' % (self.__class__.__name__, self.items())
149         finally:
150             del _repr_running[call_key]
151 
152     def __reduce__(self):
153         'Return state information for pickling'
154         items = [[k, self[k]] for k in self]
155         inst_dict = vars(self).copy()
156         for k in vars(OrderedDict()):
157             inst_dict.pop(k, None)
158         if inst_dict:
159             return (self.__class__, (items,), inst_dict)
160         return self.__class__, (items,)
161 
162     def copy(self):
163         'od.copy() -> a shallow copy of od'
164         return self.__class__(self)
165 
166     @classmethod
167     def fromkeys(cls, iterable, value=None):
168         '''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S.
169         If not specified, the value defaults to None.
170 
171         '''
172         self = cls()
173         for key in iterable:
174             self[key] = value
175         return self
176 
177     def __eq__(self, other):
178         '''od.__eq__(y) <==> od==y.  Comparison to another OD is order-sensitive
179         while comparison to a regular mapping is order-insensitive.
180 
181         '''
182         if isinstance(other, OrderedDict):
183             return dict.__eq__(self, other) and all(_imap(_eq, self, other))
184         return dict.__eq__(self, other)
185 
186     def __ne__(self, other):
187         'od.__ne__(y) <==> od!=y'
188         return not self == other
189 
190     # -- the following methods support python 3.x style dictionary views --
191 
192     def viewkeys(self):
193         "od.viewkeys() -> a set-like object providing a view on od's keys"
194         return KeysView(self)
195 
196     def viewvalues(self):
197         "od.viewvalues() -> an object providing a view on od's values"
198         return ValuesView(self)
199 
200     def viewitems(self):
201         "od.viewitems() -> a set-like object providing a view on od's items"
202         return ItemsView(self)
OrderdDict Code

我们都知道字典本来是无序的,它依靠key,value之间的索引进行匹配,那么有序字典的原理是什么呢? 原理: dic = {'k2':1,'k1':2},li = ['k1','k2'],这个字典在内部维护了一个key列表。

 

从上面的图中我们就知道,尽管我们定义的字典是从1到8按顺序写的,但是在打印的过程当中并没有按到我们希望的顺序打印。这个时候有序字典的优势就出来了:

3、默认字典(defaultdict) 

defaultdict是对字典的类型的补充,他默认给字典的值设置了一个类型。

 1 class defaultdict(dict):
 2     """
 3     defaultdict(default_factory[, ...]) --> dict with default factory
 4     
 5     The default factory is called without arguments to produce
 6     a new value when a key is not present, in __getitem__ only.
 7     A defaultdict compares equal to a dict with the same items.
 8     All remaining arguments are treated the same as if they were
 9     passed to the dict constructor, including keyword arguments.
10     """
11     def copy(self): # real signature unknown; restored from __doc__
12         """ D.copy() -> a shallow copy of D. """
13         pass
14 
15     def __copy__(self, *args, **kwargs): # real signature unknown
16         """ D.copy() -> a shallow copy of D. """
17         pass
18 
19     def __getattribute__(self, name): # real signature unknown; restored from __doc__
20         """ x.__getattribute__('name') <==> x.name """
21         pass
22 
23     def __init__(self, default_factory=None, **kwargs): # known case of _collections.defaultdict.__init__
24         """
25         defaultdict(default_factory[, ...]) --> dict with default factory
26         
27         The default factory is called without arguments to produce
28         a new value when a key is not present, in __getitem__ only.
29         A defaultdict compares equal to a dict with the same items.
30         All remaining arguments are treated the same as if they were
31         passed to the dict constructor, including keyword arguments.
32         
33         # (copied from class doc)
34         """
35         pass
36 
37     def __missing__(self, key): # real signature unknown; restored from __doc__
38         """
39         __missing__(key) # Called by __getitem__ for missing key; pseudo-code:
40           if self.default_factory is None: raise KeyError((key,))
41           self[key] = value = self.default_factory()
42           return value
43         """
44         pass
45 
46     def __reduce__(self, *args, **kwargs): # real signature unknown
47         """ Return state information for pickling. """
48         pass
49 
50     def __repr__(self): # real signature unknown; restored from __doc__
51         """ x.__repr__() <==> repr(x) """
52         pass
53 
54     default_factory = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
55     """Factory for default value called by __missing__()."""
56 
57 defaultdict
defaultdict Code

用代码实现了下述功能

有如下值集合 [11,22,33,44,55,66,77,88,99,90...],将所有大于 66 的值保存至字典的第一个key中,将小于 66 的值保存至第二个key的值中。
即: {'k1': 大于66 , 'k2': 小于66}

看出神奇的地方了么?我们可以不需要在空字典中指定value的值,直接执行append,就可以向字典中插入值了,就是因为我们使用defauldict(list)方式定义了一个value值默认为list的字典。

否则我们就要这么写才行:

 1 lst = [11,22,33,44,55,66,77,88,99,90]
 2 dic = {}
 3 for l in lst:
 4     if l >= 66:
 5         if 'k2'in dic.keys():
 6             dic['k2'].append(l)
 7         else:
 8             dic['k2'] = [l,]
 9     else:
10         if 'k1'in dic.keys():
11             dic['k1'].append(l)
12         else:
13             dic['k1'] = [l,]
14 print dic
普通字典的实现方式

4、可命名元组(namedtuple) 

根据nametuple可以创建一个包含tuple所有功能以及其他功能的类型。

  1 class Mytuple(__builtin__.tuple)
  2  |  Mytuple(x, y)
  3  |  
  4  |  Method resolution order:
  5  |      Mytuple
  6  |      __builtin__.tuple
  7  |      __builtin__.object
  8  |  
  9  |  Methods defined here:
 10  |  
 11  |  __getnewargs__(self)
 12  |      Return self as a plain tuple.  Used by copy and pickle.
 13  |  
 14  |  __getstate__(self)
 15  |      Exclude the OrderedDict from pickling
 16  |  
 17  |  __repr__(self)
 18  |      Return a nicely formatted representation string
 19  |  
 20  |  _asdict(self)
 21  |      Return a new OrderedDict which maps field names to their values
 22  |  
 23  |  _replace(_self, **kwds)
 24  |      Return a new Mytuple object replacing specified fields with new values
 25  |  
 26  |  ----------------------------------------------------------------------
 27  |  Class methods defined here:
 28  |  
 29  |  _make(cls, iterable, new=<built-in method __new__ of type object>, len=<built-in function len>) from __builtin__.type
 30  |      Make a new Mytuple object from a sequence or iterable
 31  |  
 32  |  ----------------------------------------------------------------------
 33  |  Static methods defined here:
 34  |  
 35  |  __new__(_cls, x, y)
 36  |      Create new instance of Mytuple(x, y)
 37  |  
 38  |  ----------------------------------------------------------------------
 39  |  Data descriptors defined here:
 40  |  
 41  |  __dict__
 42  |      Return a new OrderedDict which maps field names to their values
 43  |  
 44  |  x
 45  |      Alias for field number 0
 46  |  
 47  |  y
 48  |      Alias for field number 1
 49  |  
 50  |  ----------------------------------------------------------------------
 51  |  Data and other attributes defined here:
 52  |  
 53  |  _fields = ('x', 'y')
 54  |  
 55  |  ----------------------------------------------------------------------
 56  |  Methods inherited from __builtin__.tuple:
 57  |  
 58  |  __add__(...)
 59  |      x.__add__(y) <==> x+y
 60  |  
 61  |  __contains__(...)
 62  |      x.__contains__(y) <==> y in x
 63  |  
 64  |  __eq__(...)
 65  |      x.__eq__(y) <==> x==y
 66  |  
 67  |  __ge__(...)
 68  |      x.__ge__(y) <==> x>=y
 69  |  
 70  |  __getattribute__(...)
 71  |      x.__getattribute__('name') <==> x.name
 72  |  
 73  |  __getitem__(...)
 74  |      x.__getitem__(y) <==> x[y]
 75  |  
 76  |  __getslice__(...)
 77  |      x.__getslice__(i, j) <==> x[i:j]
 78  |      
 79  |      Use of negative indices is not supported.
 80  |  
 81  |  __gt__(...)
 82  |      x.__gt__(y) <==> x>y
 83  |  
 84  |  __hash__(...)
 85  |      x.__hash__() <==> hash(x)
 86  |  
 87  |  __iter__(...)
 88  |      x.__iter__() <==> iter(x)
 89  |  
 90  |  __le__(...)
 91  |      x.__le__(y) <==> x<=y
 92  |  
 93  |  __len__(...)
 94  |      x.__len__() <==> len(x)
 95  |  
 96  |  __lt__(...)
 97  |      x.__lt__(y) <==> x<y
 98  |  
 99  |  __mul__(...)
100  |      x.__mul__(n) <==> x*n
101  |  
102  |  __ne__(...)
103  |      x.__ne__(y) <==> x!=y
104  |  
105  |  __rmul__(...)
106  |      x.__rmul__(n) <==> n*x
107  |  
108  |  __sizeof__(...)
109  |      T.__sizeof__() -- size of T in memory, in bytes
110  |  
111  |  count(...)
112  |      T.count(value) -> integer -- return number of occurrences of value
113  |  
114  |  index(...)
115  |      T.index(value, [start, [stop]]) -> integer -- return first index of value.
116  |      Raises ValueError if the value is not present.
117 
118 Mytuple
119 
120 Mytuple
namedtuple Code

 主要用于‘坐标’的表示。用法如下:

5、双向队列(deque)

一个线程安全的双向队列:双向队列我们可以理解为两个栈底相连的栈,和队列的先进先出不同,元素可以从这个队列的两端分别加入或者删除值。尽管list其实完全可以实现这个功能,但是python的collections类还是很贴心的把这些方法都归纳了出来,歪果仁就是有意思啊~~~

  1 class deque(object):
  2     """
  3     deque([iterable[, maxlen]]) --> deque object
  4     
  5     Build an ordered collection with optimized access from its endpoints.
  6     """
  7     def append(self, *args, **kwargs): # real signature unknown
  8         """ Add an element to the right side of the deque. """
  9         pass
 10 
 11     def appendleft(self, *args, **kwargs): # real signature unknown
 12         """ Add an element to the left side of the deque. """
 13         pass
 14 
 15     def clear(self, *args, **kwargs): # real signature unknown
 16         """ Remove all elements from the deque. """
 17         pass
 18 
 19     def count(self, value): # real signature unknown; restored from __doc__
 20         """ D.count(value) -> integer -- return number of occurrences of value """
 21         return 0
 22 
 23     def extend(self, *args, **kwargs): # real signature unknown
 24         """ Extend the right side of the deque with elements from the iterable """
 25         pass
 26 
 27     def extendleft(self, *args, **kwargs): # real signature unknown
 28         """ Extend the left side of the deque with elements from the iterable """
 29         pass
 30 
 31     def pop(self, *args, **kwargs): # real signature unknown
 32         """ Remove and return the rightmost element. """
 33         pass
 34 
 35     def popleft(self, *args, **kwargs): # real signature unknown
 36         """ Remove and return the leftmost element. """
 37         pass
 38 
 39     def remove(self, value): # real signature unknown; restored from __doc__
 40         """ D.remove(value) -- remove first occurrence of value. """
 41         pass
 42 
 43     def reverse(self): # real signature unknown; restored from __doc__
 44         """ D.reverse() -- reverse *IN PLACE* """
 45         pass
 46 
 47     def rotate(self, *args, **kwargs): # real signature unknown
 48         """ Rotate the deque n steps to the right (default n=1).  If n is negative, rotates left. """
 49         pass
 50 
 51     def __copy__(self, *args, **kwargs): # real signature unknown
 52         """ Return a shallow copy of a deque. """
 53         pass
 54 
 55     def __delitem__(self, y): # real signature unknown; restored from __doc__
 56         """ x.__delitem__(y) <==> del x[y] """
 57         pass
 58 
 59     def __eq__(self, y): # real signature unknown; restored from __doc__
 60         """ x.__eq__(y) <==> x==y """
 61         pass
 62 
 63     def __getattribute__(self, name): # real signature unknown; restored from __doc__
 64         """ x.__getattribute__('name') <==> x.name """
 65         pass
 66 
 67     def __getitem__(self, y): # real signature unknown; restored from __doc__
 68         """ x.__getitem__(y) <==> x[y] """
 69         pass
 70 
 71     def __ge__(self, y): # real signature unknown; restored from __doc__
 72         """ x.__ge__(y) <==> x>=y """
 73         pass
 74 
 75     def __gt__(self, y): # real signature unknown; restored from __doc__
 76         """ x.__gt__(y) <==> x>y """
 77         pass
 78 
 79     def __iadd__(self, y): # real signature unknown; restored from __doc__
 80         """ x.__iadd__(y) <==> x+=y """
 81         pass
 82 
 83     def __init__(self, iterable=(), maxlen=None): # known case of _collections.deque.__init__
 84         """
 85         deque([iterable[, maxlen]]) --> deque object
 86         
 87         Build an ordered collection with optimized access from its endpoints.
 88         # (copied from class doc)
 89         """
 90         pass
 91 
 92     def __iter__(self): # real signature unknown; restored from __doc__
 93         """ x.__iter__() <==> iter(x) """
 94         pass
 95 
 96     def __len__(self): # real signature unknown; restored from __doc__
 97         """ x.__len__() <==> len(x) """
 98         pass
 99 
100     def __le__(self, y): # real signature unknown; restored from __doc__
101         """ x.__le__(y) <==> x<=y """
102         pass
103 
104     def __lt__(self, y): # real signature unknown; restored from __doc__
105         """ x.__lt__(y) <==> x<y """
106         pass
107 
108     @staticmethod # known case of __new__
109     def __new__(S, *more): # real signature unknown; restored from __doc__
110         """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
111         pass
112 
113     def __ne__(self, y): # real signature unknown; restored from __doc__
114         """ x.__ne__(y) <==> x!=y """
115         pass
116 
117     def __reduce__(self, *args, **kwargs): # real signature unknown
118         """ Return state information for pickling. """
119         pass
120 
121     def __repr__(self): # real signature unknown; restored from __doc__
122         """ x.__repr__() <==> repr(x) """
123         pass
124 
125     def __reversed__(self): # real signature unknown; restored from __doc__
126         """ D.__reversed__() -- return a reverse iterator over the deque """
127         pass
128 
129     def __setitem__(self, i, y): # real signature unknown; restored from __doc__
130         """ x.__setitem__(i, y) <==> x[i]=y """
131         pass
132 
133     def __sizeof__(self): # real signature unknown; restored from __doc__
134         """ D.__sizeof__() -- size of D in memory, in bytes """
135         pass
136 
137     maxlen = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
138     """maximum size of a deque or None if unbounded"""
139 
140 
141     __hash__ = None
142 
143 deque
deque Code

 

原文地址:https://www.cnblogs.com/Eva-J/p/4962618.html