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Diffstat (limited to 'lib/python2.7/collections.py')
| -rw-r--r-- | lib/python2.7/collections.py | 693 |
1 files changed, 693 insertions, 0 deletions
diff --git a/lib/python2.7/collections.py b/lib/python2.7/collections.py new file mode 100644 index 0000000..af32e44 --- /dev/null +++ b/lib/python2.7/collections.py @@ -0,0 +1,693 @@ +__all__ = ['Counter', 'deque', 'defaultdict', 'namedtuple', 'OrderedDict'] +# For bootstrapping reasons, the collection ABCs are defined in _abcoll.py. +# They should however be considered an integral part of collections.py. +from _abcoll import * +import _abcoll +__all__ += _abcoll.__all__ + +from _collections import deque, defaultdict +from operator import itemgetter as _itemgetter, eq as _eq +from keyword import iskeyword as _iskeyword +import sys as _sys +import heapq as _heapq +from itertools import repeat as _repeat, chain as _chain, starmap as _starmap +from itertools import imap as _imap + +try: + from thread import get_ident as _get_ident +except ImportError: + from dummy_thread import get_ident as _get_ident + + +################################################################################ +### OrderedDict +################################################################################ + +class OrderedDict(dict): + 'Dictionary that remembers insertion order' + # An inherited dict maps keys to values. + # The inherited dict provides __getitem__, __len__, __contains__, and get. + # The remaining methods are order-aware. + # Big-O running times for all methods are the same as regular dictionaries. + + # The internal self.__map dict maps keys to links in a doubly linked list. + # The circular doubly linked list starts and ends with a sentinel element. + # The sentinel element never gets deleted (this simplifies the algorithm). + # Each link is stored as a list of length three: [PREV, NEXT, KEY]. + + def __init__(self, *args, **kwds): + '''Initialize an ordered dictionary. The signature is the same as + regular dictionaries, but keyword arguments are not recommended because + their insertion order is arbitrary. + + ''' + if len(args) > 1: + raise TypeError('expected at most 1 arguments, got %d' % len(args)) + try: + self.__root + except AttributeError: + self.__root = root = [] # sentinel node + root[:] = [root, root, None] + self.__map = {} + self.__update(*args, **kwds) + + def __setitem__(self, key, value, dict_setitem=dict.__setitem__): + 'od.__setitem__(i, y) <==> od[i]=y' + # Setting a new item creates a new link at the end of the linked list, + # and the inherited dictionary is updated with the new key/value pair. + if key not in self: + root = self.__root + last = root[0] + last[1] = root[0] = self.__map[key] = [last, root, key] + return dict_setitem(self, key, value) + + def __delitem__(self, key, dict_delitem=dict.__delitem__): + 'od.__delitem__(y) <==> del od[y]' + # Deleting an existing item uses self.__map to find the link which gets + # removed by updating the links in the predecessor and successor nodes. + dict_delitem(self, key) + link_prev, link_next, _ = self.__map.pop(key) + link_prev[1] = link_next # update link_prev[NEXT] + link_next[0] = link_prev # update link_next[PREV] + + def __iter__(self): + 'od.__iter__() <==> iter(od)' + # Traverse the linked list in order. + root = self.__root + curr = root[1] # start at the first node + while curr is not root: + yield curr[2] # yield the curr[KEY] + curr = curr[1] # move to next node + + def __reversed__(self): + 'od.__reversed__() <==> reversed(od)' + # Traverse the linked list in reverse order. + root = self.__root + curr = root[0] # start at the last node + while curr is not root: + yield curr[2] # yield the curr[KEY] + curr = curr[0] # move to previous node + + def clear(self): + 'od.clear() -> None. Remove all items from od.' + root = self.__root + root[:] = [root, root, None] + self.__map.clear() + dict.clear(self) + + # -- the following methods do not depend on the internal structure -- + + def keys(self): + 'od.keys() -> list of keys in od' + return list(self) + + def values(self): + 'od.values() -> list of values in od' + return [self[key] for key in self] + + def items(self): + 'od.items() -> list of (key, value) pairs in od' + return [(key, self[key]) for key in self] + + def iterkeys(self): + 'od.iterkeys() -> an iterator over the keys in od' + return iter(self) + + def itervalues(self): + 'od.itervalues -> an iterator over the values in od' + for k in self: + yield self[k] + + def iteritems(self): + 'od.iteritems -> an iterator over the (key, value) pairs in od' + for k in self: + yield (k, self[k]) + + update = MutableMapping.update + + __update = update # let subclasses override update without breaking __init__ + + __marker = object() + + def pop(self, key, default=__marker): + '''od.pop(k[,d]) -> v, remove specified key and return the corresponding + value. If key is not found, d is returned if given, otherwise KeyError + is raised. + + ''' + if key in self: + result = self[key] + del self[key] + return result + if default is self.__marker: + raise KeyError(key) + return default + + def setdefault(self, key, default=None): + 'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od' + if key in self: + return self[key] + self[key] = default + return default + + def popitem(self, last=True): + '''od.popitem() -> (k, v), return and remove a (key, value) pair. + Pairs are returned in LIFO order if last is true or FIFO order if false. + + ''' + if not self: + raise KeyError('dictionary is empty') + key = next(reversed(self) if last else iter(self)) + value = self.pop(key) + return key, value + + def __repr__(self, _repr_running={}): + 'od.__repr__() <==> repr(od)' + call_key = id(self), _get_ident() + if call_key in _repr_running: + return '...' + _repr_running[call_key] = 1 + try: + if not self: + return '%s()' % (self.__class__.__name__,) + return '%s(%r)' % (self.__class__.__name__, self.items()) + finally: + del _repr_running[call_key] + + def __reduce__(self): + 'Return state information for pickling' + items = [[k, self[k]] for k in self] + inst_dict = vars(self).copy() + for k in vars(OrderedDict()): + inst_dict.pop(k, None) + if inst_dict: + return (self.__class__, (items,), inst_dict) + return self.__class__, (items,) + + def copy(self): + 'od.copy() -> a shallow copy of od' + return self.__class__(self) + + @classmethod + def fromkeys(cls, iterable, value=None): + '''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S. + If not specified, the value defaults to None. + + ''' + self = cls() + for key in iterable: + self[key] = value + return self + + def __eq__(self, other): + '''od.__eq__(y) <==> od==y. Comparison to another OD is order-sensitive + while comparison to a regular mapping is order-insensitive. + + ''' + if isinstance(other, OrderedDict): + return dict.__eq__(self, other) and all(_imap(_eq, self, other)) + return dict.__eq__(self, other) + + def __ne__(self, other): + 'od.__ne__(y) <==> od!=y' + return not self == other + + # -- the following methods support python 3.x style dictionary views -- + + def viewkeys(self): + "od.viewkeys() -> a set-like object providing a view on od's keys" + return KeysView(self) + + def viewvalues(self): + "od.viewvalues() -> an object providing a view on od's values" + return ValuesView(self) + + def viewitems(self): + "od.viewitems() -> a set-like object providing a view on od's items" + return ItemsView(self) + + +################################################################################ +### namedtuple +################################################################################ + +_class_template = '''\ +class {typename}(tuple): + '{typename}({arg_list})' + + __slots__ = () + + _fields = {field_names!r} + + def __new__(_cls, {arg_list}): + 'Create new instance of {typename}({arg_list})' + return _tuple.__new__(_cls, ({arg_list})) + + @classmethod + def _make(cls, iterable, new=tuple.__new__, len=len): + 'Make a new {typename} object from a sequence or iterable' + result = new(cls, iterable) + if len(result) != {num_fields:d}: + raise TypeError('Expected {num_fields:d} arguments, got %d' % len(result)) + return result + + def __repr__(self): + 'Return a nicely formatted representation string' + return '{typename}({repr_fmt})' % self + + def _asdict(self): + 'Return a new OrderedDict which maps field names to their values' + return OrderedDict(zip(self._fields, self)) + + def _replace(_self, **kwds): + 'Return a new {typename} object replacing specified fields with new values' + result = _self._make(map(kwds.pop, {field_names!r}, _self)) + if kwds: + raise ValueError('Got unexpected field names: %r' % kwds.keys()) + return result + + def __getnewargs__(self): + 'Return self as a plain tuple. Used by copy and pickle.' + return tuple(self) + +{field_defs} +''' + +_repr_template = '{name}=%r' + +_field_template = '''\ + {name} = _property(_itemgetter({index:d}), doc='Alias for field number {index:d}') +''' + +def namedtuple(typename, field_names, verbose=False, rename=False): + """Returns a new subclass of tuple with named fields. + + >>> Point = namedtuple('Point', ['x', 'y']) + >>> Point.__doc__ # docstring for the new class + 'Point(x, y)' + >>> p = Point(11, y=22) # instantiate with positional args or keywords + >>> p[0] + p[1] # indexable like a plain tuple + 33 + >>> x, y = p # unpack like a regular tuple + >>> x, y + (11, 22) + >>> p.x + p.y # fields also accessable by name + 33 + >>> d = p._asdict() # convert to a dictionary + >>> d['x'] + 11 + >>> Point(**d) # convert from a dictionary + Point(x=11, y=22) + >>> p._replace(x=100) # _replace() is like str.replace() but targets named fields + Point(x=100, y=22) + + """ + + # Validate the field names. At the user's option, either generate an error + # message or automatically replace the field name with a valid name. + if isinstance(field_names, basestring): + field_names = field_names.replace(',', ' ').split() + field_names = map(str, field_names) + if rename: + seen = set() + for index, name in enumerate(field_names): + if (not all(c.isalnum() or c=='_' for c in name) + or _iskeyword(name) + or not name + or name[0].isdigit() + or name.startswith('_') + or name in seen): + field_names[index] = '_%d' % index + seen.add(name) + for name in [typename] + field_names: + if not all(c.isalnum() or c=='_' for c in name): + raise ValueError('Type names and field names can only contain ' + 'alphanumeric characters and underscores: %r' % name) + if _iskeyword(name): + raise ValueError('Type names and field names cannot be a ' + 'keyword: %r' % name) + if name[0].isdigit(): + raise ValueError('Type names and field names cannot start with ' + 'a number: %r' % name) + seen = set() + for name in field_names: + if name.startswith('_') and not rename: + raise ValueError('Field names cannot start with an underscore: ' + '%r' % name) + if name in seen: + raise ValueError('Encountered duplicate field name: %r' % name) + seen.add(name) + + # Fill-in the class template + class_definition = _class_template.format( + typename = typename, + field_names = tuple(field_names), + num_fields = len(field_names), + arg_list = repr(tuple(field_names)).replace("'", "")[1:-1], + repr_fmt = ', '.join(_repr_template.format(name=name) + for name in field_names), + field_defs = '\n'.join(_field_template.format(index=index, name=name) + for index, name in enumerate(field_names)) + ) + if verbose: + print class_definition + + # Execute the template string in a temporary namespace and support + # tracing utilities by setting a value for frame.f_globals['__name__'] + namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename, + OrderedDict=OrderedDict, _property=property, _tuple=tuple) + try: + exec class_definition in namespace + except SyntaxError as e: + raise SyntaxError(e.message + ':\n' + class_definition) + result = namespace[typename] + + # For pickling to work, the __module__ variable needs to be set to the frame + # where the named tuple is created. Bypass this step in enviroments where + # sys._getframe is not defined (Jython for example) or sys._getframe is not + # defined for arguments greater than 0 (IronPython). + try: + result.__module__ = _sys._getframe(1).f_globals.get('__name__', '__main__') + except (AttributeError, ValueError): + pass + + return result + + +######################################################################## +### Counter +######################################################################## + +class Counter(dict): + '''Dict subclass for counting hashable items. Sometimes called a bag + or multiset. Elements are stored as dictionary keys and their counts + are stored as dictionary values. + + >>> c = Counter('abcdeabcdabcaba') # count elements from a string + + >>> c.most_common(3) # three most common elements + [('a', 5), ('b', 4), ('c', 3)] + >>> sorted(c) # list all unique elements + ['a', 'b', 'c', 'd', 'e'] + >>> ''.join(sorted(c.elements())) # list elements with repetitions + 'aaaaabbbbcccdde' + >>> sum(c.values()) # total of all counts + 15 + + >>> c['a'] # count of letter 'a' + 5 + >>> for elem in 'shazam': # update counts from an iterable + ... c[elem] += 1 # by adding 1 to each element's count + >>> c['a'] # now there are seven 'a' + 7 + >>> del c['b'] # remove all 'b' + >>> c['b'] # now there are zero 'b' + 0 + + >>> d = Counter('simsalabim') # make another counter + >>> c.update(d) # add in the second counter + >>> c['a'] # now there are nine 'a' + 9 + + >>> c.clear() # empty the counter + >>> c + Counter() + + Note: If a count is set to zero or reduced to zero, it will remain + in the counter until the entry is deleted or the counter is cleared: + + >>> c = Counter('aaabbc') + >>> c['b'] -= 2 # reduce the count of 'b' by two + >>> c.most_common() # 'b' is still in, but its count is zero + [('a', 3), ('c', 1), ('b', 0)] + + ''' + # References: + # http://en.wikipedia.org/wiki/Multiset + # http://www.gnu.org/software/smalltalk/manual-base/html_node/Bag.html + # http://www.demo2s.com/Tutorial/Cpp/0380__set-multiset/Catalog0380__set-multiset.htm + # http://code.activestate.com/recipes/259174/ + # Knuth, TAOCP Vol. II section 4.6.3 + + def __init__(self, iterable=None, **kwds): + '''Create a new, empty Counter object. And if given, count elements + from an input iterable. Or, initialize the count from another mapping + of elements to their counts. + + >>> c = Counter() # a new, empty counter + >>> c = Counter('gallahad') # a new counter from an iterable + >>> c = Counter({'a': 4, 'b': 2}) # a new counter from a mapping + >>> c = Counter(a=4, b=2) # a new counter from keyword args + + ''' + super(Counter, self).__init__() + self.update(iterable, **kwds) + + def __missing__(self, key): + 'The count of elements not in the Counter is zero.' + # Needed so that self[missing_item] does not raise KeyError + return 0 + + def most_common(self, n=None): + '''List the n most common elements and their counts from the most + common to the least. If n is None, then list all element counts. + + >>> Counter('abcdeabcdabcaba').most_common(3) + [('a', 5), ('b', 4), ('c', 3)] + + ''' + # Emulate Bag.sortedByCount from Smalltalk + if n is None: + return sorted(self.iteritems(), key=_itemgetter(1), reverse=True) + return _heapq.nlargest(n, self.iteritems(), key=_itemgetter(1)) + + def elements(self): + '''Iterator over elements repeating each as many times as its count. + + >>> c = Counter('ABCABC') + >>> sorted(c.elements()) + ['A', 'A', 'B', 'B', 'C', 'C'] + + # Knuth's example for prime factors of 1836: 2**2 * 3**3 * 17**1 + >>> prime_factors = Counter({2: 2, 3: 3, 17: 1}) + >>> product = 1 + >>> for factor in prime_factors.elements(): # loop over factors + ... product *= factor # and multiply them + >>> product + 1836 + + Note, if an element's count has been set to zero or is a negative + number, elements() will ignore it. + + ''' + # Emulate Bag.do from Smalltalk and Multiset.begin from C++. + return _chain.from_iterable(_starmap(_repeat, self.iteritems())) + + # Override dict methods where necessary + + @classmethod + def fromkeys(cls, iterable, v=None): + # There is no equivalent method for counters because setting v=1 + # means that no element can have a count greater than one. + raise NotImplementedError( + 'Counter.fromkeys() is undefined. Use Counter(iterable) instead.') + + def update(self, iterable=None, **kwds): + '''Like dict.update() but add counts instead of replacing them. + + Source can be an iterable, a dictionary, or another Counter instance. + + >>> c = Counter('which') + >>> c.update('witch') # add elements from another iterable + >>> d = Counter('watch') + >>> c.update(d) # add elements from another counter + >>> c['h'] # four 'h' in which, witch, and watch + 4 + + ''' + # The regular dict.update() operation makes no sense here because the + # replace behavior results in the some of original untouched counts + # being mixed-in with all of the other counts for a mismash that + # doesn't have a straight-forward interpretation in most counting + # contexts. Instead, we implement straight-addition. Both the inputs + # and outputs are allowed to contain zero and negative counts. + + if iterable is not None: + if isinstance(iterable, Mapping): + if self: + self_get = self.get + for elem, count in iterable.iteritems(): + self[elem] = self_get(elem, 0) + count + else: + super(Counter, self).update(iterable) # fast path when counter is empty + else: + self_get = self.get + for elem in iterable: + self[elem] = self_get(elem, 0) + 1 + if kwds: + self.update(kwds) + + def subtract(self, iterable=None, **kwds): + '''Like dict.update() but subtracts counts instead of replacing them. + Counts can be reduced below zero. Both the inputs and outputs are + allowed to contain zero and negative counts. + + Source can be an iterable, a dictionary, or another Counter instance. + + >>> c = Counter('which') + >>> c.subtract('witch') # subtract elements from another iterable + >>> c.subtract(Counter('watch')) # subtract elements from another counter + >>> c['h'] # 2 in which, minus 1 in witch, minus 1 in watch + 0 + >>> c['w'] # 1 in which, minus 1 in witch, minus 1 in watch + -1 + + ''' + if iterable is not None: + self_get = self.get + if isinstance(iterable, Mapping): + for elem, count in iterable.items(): + self[elem] = self_get(elem, 0) - count + else: + for elem in iterable: + self[elem] = self_get(elem, 0) - 1 + if kwds: + self.subtract(kwds) + + def copy(self): + 'Return a shallow copy.' + return self.__class__(self) + + def __reduce__(self): + return self.__class__, (dict(self),) + + def __delitem__(self, elem): + 'Like dict.__delitem__() but does not raise KeyError for missing values.' + if elem in self: + super(Counter, self).__delitem__(elem) + + def __repr__(self): + if not self: + return '%s()' % self.__class__.__name__ + items = ', '.join(map('%r: %r'.__mod__, self.most_common())) + return '%s({%s})' % (self.__class__.__name__, items) + + # Multiset-style mathematical operations discussed in: + # Knuth TAOCP Volume II section 4.6.3 exercise 19 + # and at http://en.wikipedia.org/wiki/Multiset + # + # Outputs guaranteed to only include positive counts. + # + # To strip negative and zero counts, add-in an empty counter: + # c += Counter() + + def __add__(self, other): + '''Add counts from two counters. + + >>> Counter('abbb') + Counter('bcc') + Counter({'b': 4, 'c': 2, 'a': 1}) + + ''' + if not isinstance(other, Counter): + return NotImplemented + result = Counter() + for elem, count in self.items(): + newcount = count + other[elem] + if newcount > 0: + result[elem] = newcount + for elem, count in other.items(): + if elem not in self and count > 0: + result[elem] = count + return result + + def __sub__(self, other): + ''' Subtract count, but keep only results with positive counts. + + >>> Counter('abbbc') - Counter('bccd') + Counter({'b': 2, 'a': 1}) + + ''' + if not isinstance(other, Counter): + return NotImplemented + result = Counter() + for elem, count in self.items(): + newcount = count - other[elem] + if newcount > 0: + result[elem] = newcount + for elem, count in other.items(): + if elem not in self and count < 0: + result[elem] = 0 - count + return result + + def __or__(self, other): + '''Union is the maximum of value in either of the input counters. + + >>> Counter('abbb') | Counter('bcc') + Counter({'b': 3, 'c': 2, 'a': 1}) + + ''' + if not isinstance(other, Counter): + return NotImplemented + result = Counter() + for elem, count in self.items(): + other_count = other[elem] + newcount = other_count if count < other_count else count + if newcount > 0: + result[elem] = newcount + for elem, count in other.items(): + if elem not in self and count > 0: + result[elem] = count + return result + + def __and__(self, other): + ''' Intersection is the minimum of corresponding counts. + + >>> Counter('abbb') & Counter('bcc') + Counter({'b': 1}) + + ''' + if not isinstance(other, Counter): + return NotImplemented + result = Counter() + for elem, count in self.items(): + other_count = other[elem] + newcount = count if count < other_count else other_count + if newcount > 0: + result[elem] = newcount + return result + + +if __name__ == '__main__': + # verify that instances can be pickled + from cPickle import loads, dumps + Point = namedtuple('Point', 'x, y', True) + p = Point(x=10, y=20) + assert p == loads(dumps(p)) + + # test and demonstrate ability to override methods + class Point(namedtuple('Point', 'x y')): + __slots__ = () + @property + def hypot(self): + return (self.x ** 2 + self.y ** 2) ** 0.5 + def __str__(self): + return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y, self.hypot) + + for p in Point(3, 4), Point(14, 5/7.): + print p + + class Point(namedtuple('Point', 'x y')): + 'Point class with optimized _make() and _replace() without error-checking' + __slots__ = () + _make = classmethod(tuple.__new__) + def _replace(self, _map=map, **kwds): + return self._make(_map(kwds.get, ('x', 'y'), self)) + + print Point(11, 22)._replace(x=100) + + Point3D = namedtuple('Point3D', Point._fields + ('z',)) + print Point3D.__doc__ + + import doctest + TestResults = namedtuple('TestResults', 'failed attempted') + print TestResults(*doctest.testmod()) |