python中的有序字典
创建有序字典
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic['k3'] = 'v3' print(dic) #输出:OrderedDict([('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3')])
clear(清空有序字典)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic.clear() print(dic) #输出:OrderedDict()
copy(拷贝)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' new_dic = dic.copy() print(new_dic) #输出:OrderedDict([('k1', 'v1'), ('k2', 'v2')])
fromkeys(指定一个列表,把列表中的值作为字典的key,生成一个字典)
import collections dic = collections.OrderedDict() name = ['tom','lucy','sam'] print(dic.fromkeys(name)) print(dic.fromkeys(name,20)) #输出:OrderedDict([('tom', None), ('lucy', None), ('sam', None)]) # OrderedDict([('tom', 20), ('lucy', 20), ('sam', 20)])
items(返回由“键值对组成元素“的列表)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' print(dic.items()) #输出:odict_items([('k1', 'v1'), ('k2', 'v2')])
keys(获取字典所有的key)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' print(dic.keys()) # 输出:odict_keys(['k1', 'k2'])
move_to_end(指定一个key,把对应的key-value移到最后)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic['k3'] = 'v3' dic.move_to_end('k1') print(dic) # 输出:OrderedDict([('k2', 'v2'), ('k3', 'v3'), ('k1', 'v1')])
pop(获取指定key的value,并在字典中删除)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic['k3'] = 'v3' k = dic.pop('k2') print(k,dic) # 输出:v2 OrderedDict([('k1', 'v1'), ('k3', 'v3')])
popitem(按照后进先出原则,删除最后加入的元素,返回key-value)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic['k3'] = 'v3' print(dic.popitem(),dic) print(dic.popitem(),dic) # 输出:('k3', 'v3') OrderedDict([('k1', 'v1'), ('k2', 'v2')]) # ('k2', 'v2') OrderedDict([('k1', 'v1')])
setdefault(获取指定key的value,如果key不存在,则创建)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic['k3'] = 'v3' val = dic.setdefault('k5') print(val,dic) # 输出:None OrderedDict([('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3'), ('k5', None)])
values(获取字典所有的value,返回一个列表)
import collections dic = collections.OrderedDict() dic['k1'] = 'v1' dic['k2'] = 'v2' dic['k3'] = 'v3' print(dic.values()) # 输出:odict_values(['v1', 'v2', 'v3'])