python中的有序字典

创建有序字典

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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')])
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clear(清空有序字典)

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import collections

dic = collections.OrderedDict()
dic['k1'] = 'v1'
dic['k2'] = 'v2'
dic.clear()
print(dic)

#输出:OrderedDict()
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copy(拷贝)

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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')])
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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)

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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)])
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items(返回由“键值对组成元素“的列表)

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import collections

dic = collections.OrderedDict()
dic['k1'] = 'v1'
dic['k2'] = 'v2'
print(dic.items())

#输出:odict_items([('k1', 'v1'), ('k2', 'v2')])
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keys(获取字典所有的key)

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import collections

dic = collections.OrderedDict()
dic['k1'] = 'v1'
dic['k2'] = 'v2'
print(dic.keys())

# 输出:odict_keys(['k1', 'k2'])
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move_to_end(指定一个key,把对应的key-value移到最后)

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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')])
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pop(获取指定key的value,并在字典中删除)

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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')])
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popitem(按照后进先出原则,删除最后加入的元素,返回key-value)

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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')])
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setdefault(获取指定key的value,如果key不存在,则创建)

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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)])
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values(获取字典所有的value,返回一个列表)

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import collections

dic = collections.OrderedDict()
dic['k1'] = 'v1'
dic['k2'] = 'v2'
dic['k3'] = 'v3'
print(dic.values())

# 输出:odict_values(['v1', 'v2', 'v3'])
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转载于:https://www.cnblogs.com/tianhen/p/9001525.html

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