默认字典defaultdict

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。

class defaultdict(dict):

"""

defaultdict(default_factory[, ...]) --> dict with default factory

The default factory is called without arguments to produce

a new value when a key is not present, in __getitem__ only.

A defaultdict compares equal to a dict with the same items.

All remaining arguments are treated the same as if they were

passed to the dict constructor, including keyword arguments.

"""

def copy(self): # real signature unknown; restored from __doc__

""" D.copy() -> a shallow copy of D. """

pass

def __copy__(self, *args, **kwargs): # real signature unknown

""" D.copy() -> a shallow copy of D. """

pass

def __getattribute__(self, name): # real signature unknown; restored from __doc__

""" x.__getattribute__('name') <==> x.name """

pass

def __init__(self, default_factory=None, **kwargs): # known case of _collections.defaultdict.__init__

"""

defaultdict(default_factory[, ...]) --> dict with default factory

The default factory is called without arguments to produce

a new value when a key is not present, in __getitem__ only.

A defaultdict compares equal to a dict with the same items.

All remaining arguments are treated the same as if they were

passed to the dict constructor, including keyword arguments.

# (copied from class doc)

"""

pass

def __missing__(self, key): # real signature unknown; restored from __doc__

"""

__missing__(key) # Called by __getitem__ for missing key; pseudo-code:

if self.default_factory is None: raise KeyError((key,))

self[key] = value = self.default_factory()

return value

"""

pass

def __reduce__(self, *args, **kwargs): # real signature unknown

""" Return state information for pickling. """

pass

def __repr__(self): # real signature unknown; restored from __doc__

""" x.__repr__() <==> repr(x) """

pass

default_factory = property(lambda self: object(), lambda self, v: None, lambda self: None) # default

"""Factory for default value called by __missing__()."""

原生字典：

values = [11, 22, 33,44,55,66,77,88,99,90]

my_dict = {}

for value in values:

if value>66:

if my_dict.has_key('k1'):

my_dict['k1'].append(value)

else:

my_dict['k1'] = [value]

else:

if my_dict.has_key('k2'):

my_dict['k2'].append(value)

else:

my_dict['k2'] = [value]

默认字典：

from collections import defaultdict

values = [11, 22, 33,44,55,66,77,88,99,90]

my_dict = defaultdict(list)

for value in values:

if value>66:

my_dict['k1'].append(value)

else:

my_dict['k2'].append(value)

defaultdict字典解决方法