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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