Python字典基础

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字典是Python唯一的映射类型(hash表)
keys() 返回键列表，values() 返回值列表，items() 返回键值对的元组，has_key(key) 返回是否含有该key

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>>> a={'name':'zhzhgo','age':25} >>> a {'age': 25, 'name': 'zhzhgo'} >>> a.keys() ['age', 'name'] >>> a.values() [25, 'zhzhgo'] >>> a.items() [('age', 25), ('name', 'zhzhgo')] >>> a.has_key('name') True >>>

用工厂方法dict()和内建方法fromkeys()创建字典

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>>> a=dict((['name','zhzhgo'],['age',25])) >>> a {'age': 25, 'name': 'zhzhgo'} >>> a={}.fromkeys(('x','y'),1) >>> a {'y': 1, 'x': 1} >>>

查看遍历字典
get()函数，有则返回，无则返回默认值

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>>> a={'name':'zhzhgo','age':25} >>> a['name'] 'zhzhgo' >>> a['age'] 25 >>> a.get('name') 'zhzhgo' >>> a.get('height',180) 180 >>> for i in a: print i,    age name >>> for i in a: print a,    25 zhzhgo >>> for k,v in a.items(): print k,v    age 25 name zhzhgo >>>

增删改字典
dict1.update(dict2) 更新dict2到dict1，无则添加，重复则覆盖

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>>> a={'name':'zhzhgo','age':25} >>> a['height']=180 >>> a {'age': 25, 'name': 'zhzhgo', 'height': 180} >>> del a['height'] >>> a {'age': 25, 'name': 'zhzhgo'} >>> b={'age':24} >>> a.update(b) >>> a {'age': 24, 'name': 'zhzhgo'} >>> b={'height':180} >>> a.update(b) >>> a {'age': 24, 'name': 'zhzhgo', 'height': 180} >>> h=a.pop('height') >>> h 180 >>> a {'age': 24, 'name': 'zhzhgo'} >>> a.clear() >>> a {} >>>

import json
json.dumps() 编码，字典转成字符串
json.loads() 解码，字符串转成字典

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>>> a={'name':'zhzhgo','age':25} >>> import json >>> json.dumps(a) '{"age": 25, "name": "zhzhgo"}' >>> b=json.loads('{"age": 25, "name": "zhzhgo"}') >>> b {u'age': 25, u'name': u'zhzhgo'} >>>