python3 OrderedDict類（有序字典），python3ordereddict

python3 OrderedDict類（有序字典），python3ordereddict

建立有序字典

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic['k3'] = 'v3'print(dic)#輸出：OrderedDict([('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3')])

clear(清空有序字典)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic.clear()print(dic)#輸出：OrderedDict()

copy(拷貝)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'new_dic = dic.copy()print(new_dic)#輸出：OrderedDict([('k1', 'v1'), ('k2', 'v2')])

fromkeys(指定一個列表，把列表中的值作為字典的key,產生一個字典)

import collectionsdic = collections.OrderedDict()name = ['tom','lucy','sam']print(dic.fromkeys(name))print(dic.fromkeys(name,20))#輸出：OrderedDict([('tom', None), ('lucy', None), ('sam', None)])#     OrderedDict([('tom', 20), ('lucy', 20), ('sam', 20)])

items(返回由“索引值對組成元素“的列表)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'print(dic.items())#輸出：odict_items([('k1', 'v1'), ('k2', 'v2')])

keys(擷取字典所有的key)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'print(dic.keys())# 輸出：odict_keys(['k1', 'k2'])

move_to_end(指定一個key，把對應的key-value移到最後)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic['k3'] = 'v3'dic.move_to_end('k1')print(dic)# 輸出：OrderedDict([('k2', 'v2'), ('k3', 'v3'), ('k1', 'v1')])

pop(擷取指定key的value，並在字典中刪除)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic['k3'] = 'v3'k = dic.pop('k2')print(k,dic)# 輸出：v2 OrderedDict([('k1', 'v1'), ('k3', 'v3')])

popitem(按照後進先出原則，刪除最後加入的元素，返回key-value)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic['k3'] = 'v3'print(dic.popitem(),dic)print(dic.popitem(),dic)# 輸出：('k3', 'v3') OrderedDict([('k1', 'v1'), ('k2', 'v2')])#      ('k2', 'v2') OrderedDict([('k1', 'v1')])

setdefault(擷取指定key的value，如果key不存在，則建立)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic['k3'] = 'v3'val = dic.setdefault('k5')print(val,dic)# 輸出：None OrderedDict([('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3'), ('k5', None)])

values(擷取字典所有的value，返回一個列表)

import collectionsdic = collections.OrderedDict()dic['k1'] = 'v1'dic['k2'] = 'v2'dic['k3'] = 'v3'print(dic.values())# 輸出：odict_values(['v1', 'v2', 'v3'])