1. Lightning Talk
collections
André Ericson
Dezembro/2011, Pug-Pe

2. collections
Roteiro
• Counter
• deque
• namedtuple
• OrderedDict
• abc
• collections.abc

3. collections.Counter

4. Counter
>>> c = Counter([’a’, ’b’, ’c’, ’d’, ’a’, ’d’, ’b’])
>>> print c
Counter({’a’: 2, ’b’: 2, ’d’: 2, ’c’: 1})
# Funciona como um dicionario
>>> print c[’a’]
2
>>> c[’a’] += 1
>>> print c
Counter({’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> print c[’e’] # Retorna 0 ao inves de levantar KeyError
0
>>> c.most_common(3)
[(’a’, 3), (’b’, 2), (’d’, 2)]
>>> c[’f’] = ’asdad’ # Pode adicionar qualquer coisa
>>> print c
Counter({’f’: ’asdad’, ’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> c[’f’] > c[’a’]
True
>>> c.update([’a’, ’b’, ’b’, ’d’])
# c.subtract(iterable-or-mapping) faz o subtracao de elementos
>>> print c
Counter({’f’: ’asdad’, ’a’: 4, ’b’: 4, ’d’: 3, ’c’: 1})

5. Counter
>>> c = Counter([’a’, ’b’, ’c’, ’d’, ’a’, ’d’, ’b’])
>>> print c
Counter({’a’: 2, ’b’: 2, ’d’: 2, ’c’: 1})
# Funciona como um dicionario
>>> print c[’a’]
2
>>> c[’a’] += 1
>>> print c
Counter({’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> print c[’e’] # Retorna 0 ao inves de levantar KeyError
0
>>> c.most_common(3)
[(’a’, 3), (’b’, 2), (’d’, 2)]
>>> c[’f’] = ’asdad’ # Pode adicionar qualquer coisa
>>> print c
Counter({’f’: ’asdad’, ’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> c[’f’] > c[’a’]
True
>>> c.update([’a’, ’b’, ’b’, ’d’])
# c.subtract(iterable-or-mapping) faz o subtracao de elementos
>>> print c
Counter({’f’: ’asdad’, ’a’: 4, ’b’: 4, ’d’: 3, ’c’: 1})

6. Counter
>>> c = Counter([’a’, ’b’, ’c’, ’d’, ’a’, ’d’, ’b’])
>>> print c
Counter({’a’: 2, ’b’: 2, ’d’: 2, ’c’: 1})
# Funciona como um dicionario
>>> print c[’a’]
2
>>> c[’a’] += 1
>>> print c
Counter({’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> print c[’e’] # Retorna 0 ao inves de levantar KeyError
0
>>> c.most_common(3)
[(’a’, 3), (’b’, 2), (’d’, 2)]
>>> c[’f’] = ’asdad’ # Pode adicionar qualquer coisa
>>> print c
Counter({’f’: ’asdad’, ’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> c[’f’] > c[’a’]
True
>>> c.update([’a’, ’b’, ’b’, ’d’])
# c.subtract(iterable-or-mapping) faz o subtracao de elementos
>>> print c
Counter({’f’: ’asdad’, ’a’: 4, ’b’: 4, ’d’: 3, ’c’: 1})

7. Counter
>>> c = Counter([’a’, ’b’, ’c’, ’d’, ’a’, ’d’, ’b’])
>>> print c
Counter({’a’: 2, ’b’: 2, ’d’: 2, ’c’: 1})
# Funciona como um dicionario
>>> print c[’a’]
2
>>> c[’a’] += 1
>>> print c
Counter({’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> print c[’e’] # Retorna 0 ao inves de levantar KeyError
0
>>> c.most_common(3)
[(’a’, 3), (’b’, 2), (’d’, 2)]
>>> c[’f’] = ’asdad’ # Pode adicionar qualquer coisa
>>> print c
Counter({’f’: ’asdad’, ’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> c[’f’] > c[’a’]
True
>>> c.update([’a’, ’b’, ’b’, ’d’])
# c.subtract(iterable-or-mapping) faz o subtracao de elementos
>>> print c
Counter({’f’: ’asdad’, ’a’: 4, ’b’: 4, ’d’: 3, ’c’: 1})

8. Counter
>>> c = Counter([’a’, ’b’, ’c’, ’d’, ’a’, ’d’, ’b’])
>>> print c
Counter({’a’: 2, ’b’: 2, ’d’: 2, ’c’: 1})
# Funciona como um dicionario
>>> print c[’a’]
2
>>> c[’a’] += 1
>>> print c
Counter({’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> print c[’e’] # Retorna 0 ao inves de levantar KeyError
0
>>> c.most_common(3)
[(’a’, 3), (’b’, 2), (’d’, 2)]
>>> c[’f’] = ’asdad’ # Pode adicionar qualquer coisa
>>> print c
Counter({’f’: ’asdad’, ’a’: 3, ’b’: 2, ’d’: 2, ’c’: 1})
>>> c[’f’] > c[’a’]
True
>>> c.update([’a’, ’b’, ’b’, ’d’])
# c.subtract(iterable-or-mapping) faz o subtracao de elementos
>>> print c
Counter({’f’: ’asdad’, ’a’: 4, ’b’: 4, ’d’: 3, ’c’: 1})

9. Counter: Exemplo
import re
from collections import Counter
LANGUAGES = [
"C", "C++", "Java", "PHP", "Ruby", "C#",
"JavaScript", "Perl", "Python"
]
swear_book = [
’shit’, ’piss’, ’fuck’,
’cock’, ’motherfucker’, Counter({’C++’: 67, ’Ruby’: 64,
] ’JavaScript’: 55, ’C’: 39,
’Perl’: 33, ’C#’: 29,
lang_count = Counter() ’Java’: 23, ’Python’: 15,
swear_count = Counter() ’PHP’: 11})
Counter({’shit’: 213, ’fuck’: 112,
for lang in LANGUAGES: ’piss’: 5, ’cock’: 4,
with open(’language-commits[’ + lang + ’motherfucker’: 2})
’].yml’) as f:
words = re.findall(’w+’, f.read().lower())
for fu in words:
if fu in swear_book:
lang_count[lang] += 1
swear_count[fu] += 1
print lang_count
print swear_count
data from: https://github.com/AndrewVos/github-statistics

10. collections.deque

11. deque
img: http://www.webreference.com

12. deque
• lists são lentas para pop(0) e insert(0, v) --> O(n)
• deque pop e insert no fim ou no início com O(1)
• deque não substitui list

13. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

14. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

15. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

16. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

17. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

18. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

19. deque
>>> d = deque([1,2,3])
>>> print d
deque([1, 2, 3])
>>> d.append(4)
>>> print d
deque([1, 2, 3, 4]) >>> d.rotate(1) # Rotaciona a direita
>>> print d
>>> d.appendleft(5) deque([9, 1, 3, 7, 8])
>>> print d
deque([5, 1, 2, 3, 4]) >>> d = deque([1,2,3], maxlen=3)
>>> print d
>>> d.pop(), d.popleft() deque([1, 2, 3], maxlen=3)
(4, 5) >>> d.append(4)
>>> del d[1] deque([2, 3, 4], maxlen=3)
>>> print d
deque([1, 3])
>>> d.extend([7, 8, 9])
>>> print d
deque([1, 3, 7, 8, 9])

20. deque vs list
num = 100000
print u"Tempo para insercao no inicio:"
print "Deque:",
print timeit.Timer(’dq.appendleft("abc")’,
’from collections import deque;’+
’dq = deque()’).timeit(number=num)
print "List:",
print timeit.Timer(’li.insert(0, "abc")’,
’li =[]’).timeit(number=num) Tempo para insercao no inicio:
print "Tempo para pop(0):" Deque: 0.0206291675568
print "Deque:", List: 5.03016710281
print timeit.Timer(’dq.popleft()’, ----------
’from collections import deque;’+ Tempo para pop(0):
’dq = deque(range(%i))’ % num Deque: 0.0202388763428
).timeit(number=num) List: 3.49450302124
print "List:", ----------
print timeit.Timer(’li.pop(0)’, Tempo de acesso ao meio:
’li = range(%i)’ % num Deque: 4.97369003296
).timeit(number=num) List: 0.051794052124
print "Tempo de acesso ao meio:"
print "Deque:",
print timeit.Timer(’dq[meio]’, ’from collections import deque;’+
’dq = deque(range(%i));’ % num +
’meio = len(dq)/2’).timeit()
print "List:",
print timeit.Timer(’li[meio]’, ’li = range(%i);’ % num +
’meio = len(li)/2’).timeit()

21. collections.namedtuple

22. namedtuple
>>> Point = namedtuple(’Point’, [’x’, ’y’])
>>> p = Point(2, 3)
>>> print p.x, p.y
2 3
>>> print p[0:2]
(2, 3)
>>> print p.count(2) # herda metodos de tuple
1
>>> Point._make([1,2])
Point(x=1, y=2)
>>> p._asdict()
OrderedDict([(’x’, 2), (’y’, 3)])
>>> p._replace(x=77)
Point(x=77, y=3)
>>> p._fields
(’x’, ’y’)

23. namedtuple
>>> Point = namedtuple(’Point’, [’x’, ’y’])
>>> p = Point(2, 3)
>>> print p.x, p.y
2 3
>>> print p[0:2]
(2, 3)
>>> print p.count(2) # herda metodos de tuple
1
>>> Point._make([1,2])
Point(x=1, y=2)
>>> p._asdict()
OrderedDict([(’x’, 2), (’y’, 3)])
>>> p._replace(x=77)
Point(x=77, y=3)
>>> p._fields
(’x’, ’y’)

24. namedtuple
>>> Point = namedtuple(’Point’, [’x’, ’y’])
>>> p = Point(2, 3)
>>> print p.x, p.y
2 3
>>> print p[0:2]
(2, 3)
>>> print p.count(2) # herda metodos de tuple
1
>>> Point._make([1,2])
Point(x=1, y=2)
>>> p._asdict()
OrderedDict([(’x’, 2), (’y’, 3)])
>>> p._replace(x=77)
Point(x=77, y=3)
>>> p._fields
(’x’, ’y’)

25. namedtuple
>>> Point = namedtuple(’Point’, [’x’, ’y’])
>>> p = Point(2, 3)
>>> print p.x, p.y
2 3
>>> print p[0:2]
(2, 3)
>>> print p.count(2) # herda metodos de tuple
1
>>> Point._make([1,2])
Point(x=1, y=2)
>>> p._asdict()
OrderedDict([(’x’, 2), (’y’, 3)])
>>> p._replace(x=77)
Point(x=77, y=3)
>>> p._fields
(’x’, ’y’)

26. namedtuple
>>> Point = namedtuple(’Point’, [’x’, ’y’])
>>> p = Point(2, 3)
>>> print p.x, p.y
2 3
>>> print p[0:2]
(2, 3)
>>> print p.count(2) # herda metodos de tuple
1
>>> Point._make([1,2])
Point(x=1, y=2)
>>> p._asdict()
OrderedDict([(’x’, 2), (’y’, 3)])
>>> p._replace(x=77)
Point(x=77, y=3)
>>> p._fields
(’x’, ’y’)

27. namedtuple
>>> Point = namedtuple(’Point’, [’x’, ’y’])
>>> p = Point(2, 3)
>>> print p.x, p.y
2 3
>>> print p[0:2]
(2, 3)
>>> print p.count(2) # herda metodos de tuple
1
>>> Point._make([1,2])
Point(x=1, y=2)
>>> p._asdict()
OrderedDict([(’x’, 2), (’y’, 3)])
>>> p._replace(x=77)
Point(x=77, y=3)
>>> p._fields
(’x’, ’y’)

28. collections.OrderedDict

29. OrderedDict
>>> d = {’banana’: 3, ’apple’:4, ’pear’: 1, ’orange’: 2}
>>> print d
{’orange’: 2, ’pear’: 1, ’banana’: 3, ’apple’: 4}
>>> print OrderedDict(sorted(d.items()))
OrderedDict([(’apple’, 4), (’banana’, 3), (’orange’, 2), (’pear’, 1)])
>>> od = OrderedDict(sorted(d.items(), key=lambda k: k[1]))
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3), (’apple’, 4)])
>>> od.popitem()
(’apple’, 4)
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3)])

30. OrderedDict
>>> d = {’banana’: 3, ’apple’:4, ’pear’: 1, ’orange’: 2}
>>> print d
{’orange’: 2, ’pear’: 1, ’banana’: 3, ’apple’: 4}
>>> print OrderedDict(sorted(d.items()))
OrderedDict([(’apple’, 4), (’banana’, 3), (’orange’, 2), (’pear’, 1)])
>>> od = OrderedDict(sorted(d.items(), key=lambda k: k[1]))
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3), (’apple’, 4)])
>>> od.popitem()
(’apple’, 4)
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3)])

31. OrderedDict
>>> d = {’banana’: 3, ’apple’:4, ’pear’: 1, ’orange’: 2}
>>> print d
{’orange’: 2, ’pear’: 1, ’banana’: 3, ’apple’: 4}
>>> print OrderedDict(sorted(d.items()))
OrderedDict([(’apple’, 4), (’banana’, 3), (’orange’, 2), (’pear’, 1)])
>>> od = OrderedDict(sorted(d.items(), key=lambda k: k[1]))
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3), (’apple’, 4)])
>>> od.popitem()
(’apple’, 4)
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3)])

32. OrderedDict
>>> d = {’banana’: 3, ’apple’:4, ’pear’: 1, ’orange’: 2}
>>> print d
{’orange’: 2, ’pear’: 1, ’banana’: 3, ’apple’: 4}
>>> print OrderedDict(sorted(d.items()))
OrderedDict([(’apple’, 4), (’banana’, 3), (’orange’, 2), (’pear’, 1)])
>>> od = OrderedDict(sorted(d.items(), key=lambda k: k[1]))
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3), (’apple’, 4)])
>>> od.popitem()
(’apple’, 4)
>>> print od
OrderedDict([(’pear’, 1), (’orange’, 2), (’banana’, 3)])

33. collections.abc
ABC - Abstract Base Class

34. abc em 2 minutos
class AbstractKnight(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def echo(self):
pass
class IncompKnight(AbstractKnight):
pass
>>> IncompKnight()
TypeError: Can’t instantiate abstract class IncompKnight
with abstract methods echo
>>> AbstractKnight.__abstractmethods__
frozenset([’echo’])
class KnightImp(AbstractKnight):
def echo(self):
print ’Ni’
>>> KnightImp().echo()
Ni

35. abc em 2 minutos
class AbstractKnight(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def echo(self):
pass
class IncompKnight(AbstractKnight):
pass
>>> IncompKnight()
TypeError: Can’t instantiate abstract class IncompKnight
with abstract methods echo
>>> AbstractKnight.__abstractmethods__
frozenset([’echo’])
class KnightImp(AbstractKnight):
def echo(self):
print ’Ni’
>>> KnightImp().echo()
Ni

36. abc em 2 minutos
class AbstractKnight(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def echo(self):
pass
class IncompKnight(AbstractKnight):
pass
>>> IncompKnight()
TypeError: Can’t instantiate abstract class IncompKnight
with abstract methods echo
>>> AbstractKnight.__abstractmethods__
frozenset([’echo’])
class KnightImp(AbstractKnight):
def echo(self):
print ’Ni’
>>> KnightImp().echo()
Ni

37. abc em 2 minutos
class AbstractKnight(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def echo(self):
pass
class IncompKnight(AbstractKnight):
pass
>>> IncompKnight()
TypeError: Can’t instantiate abstract class IncompKnight
with abstract methods echo
>>> AbstractKnight.__abstractmethods__
frozenset([’echo’])
class KnightImp(AbstractKnight):
def echo(self):
print ’Ni’
>>> KnightImp().echo()
Ni

38. abc em 2 minutos
class AbstractKnight(object):
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def echo(self):
pass
class IncompKnight(AbstractKnight):
pass
>>> IncompKnight()
TypeError: Can’t instantiate abstract class IncompKnight
with abstract methods echo
>>> AbstractKnight.__abstractmethods__
frozenset([’echo’])
class KnightImp(AbstractKnight):
def echo(self):
print ’Ni’
>>> KnightImp().echo()
Ni

39. Herdando dict
class Dicto(dict):
def __getitem__(self, k):
return 31
>>> d = Dicto()
>>> d[2]
31
>>> print d.get(2)
None
D’oh : (

40. Herdando dict
class Dicto(dict):
def __getitem__(self, k):
return 31
>>> d = Dicto()
>>> d[2]
31
>>> print d.get(2)
None
D’oh : (

41. Herdando dict
class Dicto(dict):
def __getitem__(self, k):
return 31
>>> d = Dicto()
>>> d[2]
31
>>> print d.get(2)
None
D’oh : (

42. collections.abc
• subclasses de builtin containers nem sempre produzem resultados
esperados
• subclasses de ABC produzem

43. collections.abc

44. if you’re lazy
Callable -> [’__call__’]
Container -> [’__contains__’]
Hashable -> [’__hash__’]
ItemsView -> []
Iterable -> [’__iter__’]
# ex: MutableMapping.__abstractmethods__ Iterator -> [’next’]
for i in dir(collections): KeysView -> []
try: Mapping -> [’__iter__’, ’__getitem__’, ’__len__’]
meths = list(getattr(collections, i MappingView -> []
).__abstractmethods__) MutableMapping -> [’__delitem__’, ’__setitem__’,
print i, ’->’, meths ’__getitem__’, ’__iter__’, ’__len__’]
except: MutableSequence -> [’__delitem__’, ’__setitem__’,
pass ’__getitem__’, ’__len__’, ’insert’]
MutableSet -> [’discard’, ’add’, ’__iter__’,
’__len__’, ’__contains__’]
Sequence -> [’__getitem__’, ’__len__’]
Set -> [’__iter__’, ’__len__’, ’__contains__’]
Sized -> [’__len__’]
ValuesView -> []

45. Subclassing dict de
collections.MutableMapping
from collections import MutableMapping
class Dicto(MutableMapping):
def __init__(self):
self.d = {} >>> d = Dicto()
>>> d[’eggs’] = ’ovos’
def __delitem__(self, i): >>> d[’ham’] = ’presunto’
del self.d[i] >>> for i in d:
... print i + ’:’ + d[i]
def __setitem__(self, k, v): eggs:ovos
self.d[k.lower()] = v ham:presunto
>>> d.get(’HaM’)
def __getitem__(self, k): presunto
return self.d[k.lower()] >>> d[’eGGs’]
’ovos’
def __iter__(self):
return iter(self.d)
def __len__(self):
return len(self.d)

46. Subclassing dict de
collections.MutableMapping
from collections import MutableMapping
class Dicto(MutableMapping):
def __init__(self):
self.d = {} >>> d = Dicto()
>>> d[’eggs’] = ’ovos’
def __delitem__(self, i): >>> d[’ham’] = ’presunto’
del self.d[i] >>> for i in d:
... print i + ’:’ + d[i]
def __setitem__(self, k, v): eggs:ovos
self.d[k.lower()] = v ham:presunto
>>> d.get(’HaM’)
def __getitem__(self, k): presunto
return self.d[k.lower()] >>> d[’eGGs’]
’ovos’
def __iter__(self):
return iter(self.d)
def __len__(self):
return len(self.d)

47. Referência
• Lightning Talk de:
no fisl 2011.
• The Data Structures of Python, Alex Gaynor no PyCon2011
• http://www.doughellmann.com/PyMOTW/abc/index.html
• http://docs.python.org/library/collections.html

48. Dúvidas?
André Ericson
http://www.github.com/aericson
de.ericson@gmail.com
@_aericson