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Python学习笔记6-字典
定义
使用键值对,
>>> person = {"name":"keven","age":15,"gender":"male"}>>> person[‘name‘]‘keven‘>>> type(person)<type ‘dict‘>
字典可以原地修改,即它是可变的。
>>> dict1={}>>> id(dict1)139736380198256>>> dict1["name"] = "Keven">>> id(dict1)139736380198256>>> dict1{‘name‘: ‘Keven‘}
利用元组在建构字典,方法如下:
>>> name = (["first","Google"],["second","Yahoo"])>>> website = dict(name)>>> website{‘second‘: ‘Yahoo‘, ‘first‘: ‘Google‘}
或者用这样的方法:
>>> ad = dict(name="keven", age=42)>>> ad{‘age‘: 42, ‘name‘: ‘keven‘
基本操作
• len(d),返回字典(d)中的键值对的数量
>>> city_code = {‘suzhou‘: ‘0512‘, ‘beijing‘: ‘011‘, ‘shanghai‘: ‘012‘, ‘tangshan‘: ‘0315‘}>>> len(city_code)4
• d[key],返回字典(d)中的键(key)的值
>>> city_code["suzhou"]‘0512‘
• d[key]=value,将值(value)赋给字典(d)中的键(key)
>>> city_code = {‘suzhou‘: ‘0512‘, ‘beijing‘: ‘011‘, ‘shanghai‘: ‘012‘, ‘tangshan‘: ‘0315‘}>>> city_code["shenzhen"]="1212">>> city_code{‘suzhou‘: ‘0512‘, ‘beijing‘: ‘011‘, ‘shanghai‘: ‘012‘, ‘tangshan‘: ‘0315‘, ‘shenzhen‘: ‘1212‘}
• del d[key],删除字典(d)的键(key)项(将该键值对删除)
>>> del city_code["shanghai"]>>> city_code{‘suzhou‘: ‘0512‘, ‘beijing‘: ‘011‘, ‘tangshan‘: ‘0315‘, ‘shenzhen‘: ‘1212‘}
• key in d,检查字典(d)中是否含有键为 key 的项
>>> "shenzhen" in city_codeTrue>>> "sz" in city_codeFalse
字典也可以实现格式化字符
>>> city_code = {"suzhou":"0512", "tangshan":"0315", "hangzhou":"0571"}>>> " Suzhou is a beautiful city, its area code is %(suzhou)s" % city_code‘ Suzhou is a beautiful city, its area code is 0512
Python学习笔记6-字典
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