python基本数据类型-字典

>>> dic = {'k1':'v1','k2':'v2','k3':'v3'}
>>> dic = dict(k1='v1',k2='v2')

>>> dic['k1']
'v1'
>>> dic['k2']
'v2'

>>> dic = {'k1':'v1','k2':'v2'}
>>> print(dic.get('k1'))
v1
>>> print(dic.get('k2'))
v2
>>> print(dic.get('k3'))
None
>>> print(dic.get('k3','defaultv'))
defaultv

>>> dic['k4'] = 'v4'
>>> dic
{'k3': 'v3', 'k2': 'v2', 'k1': 'v1', 'k4': 'v4'}

>>> dic = {'k1':'v1','k2':'v2'}
>>> dic.update({'k3':'v3'})
>>> print(dic)
{'k2': 'v2', 'k1': 'v1', 'k3': 'v3'}

>>> del dic['k4']
>>> dic
{'k3': 'v3', 'k2': 'v2', 'k1': 'v1'}

>>> dic = {'k1':'v1','k2':'v2'}
>>> dic.pop('k1')
'v1'
>>> dic
{'k2': 'v2'}

>>> dic.keys()
['k3', 'k2', 'k1']

>>> dic.values()
['v3', 'v2', 'v1']

>>> dic.items()
[('k3', 'v3'), ('k2', 'v2'), ('k1', 'v1')]

>>> for k,v in dic.items():
...   print(k,v)
...
('k3', 'v3')
('k2', 'v2')
('k1', 'v1')

>>> len(dic)
3

>>> dic = dict(k1='v1',k2='v2')
>>> dic
{'k2': 'v2', 'k1': 'v1'}
>>> dic.clear()
>>> dic
{}

>>> import collections>>> dic1 = collections.OrderedDict()>>> dic1['k1'] = 'v1'>>> dic1['k2'] = 'v2'>>> dic1['k3'] = 'v3'>>> print(dic1)OrderedDict([('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3')])>>>

>>> dic1 = collections.OrderedDict()>>> dic1['k1'] = 'v1'>>> dic1['k2'] = 'v2'>>> dic1['k3'] = 'v3'>>> dic1OrderedDict([('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3')])>>> dic1.pop('k2')'v2'>>> dic1OrderedDict([('k1', 'v1'), ('k3', 'v3')])>>> dic1 = collections.OrderedDict()>>> dic1['k1'] = 'v1'>>> dic1['k2'] = 'v2'>>> dic1['k3'] = 'v3'>>> dic1.popitem()('k3', 'v3')>>> dic1.popitem()('k2', 'v2')

>>> dic1 = collections.OrderedDict()>>> dic1['k1'] = 'v1'>>> dic1['k2'] = 'v2'>>> dic1['k3'] = 'v3'>>> dic1.move_to_end('k2')>>> dic1OrderedDict([('k1', 'v1'), ('k3', 'v3'), ('k2', 'v2')])

>>> dic1 = collections.defaultdict(list)>>> dic1['k1'].append('a')>>> print(dic1)defaultdict(<class 'list'>, {'k1': ['a']})