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Python字典dict使用介绍

Python 使用 介绍 字典 dict
2023-06-13 09:15:31 时间

Python字典的创建

方法一：

>>>blank_dict={} >>>product_dict={"MAC":8000,"Iphone":5000,"ipad":4000,"mp3":300} >>>product_dict {"ipad":4000,"MAC":8000,"Iphone":5000,"mp3":300} >>>blank_dict,product_dict ({},{"ipad":4000,"MAC":8000,"Iphone":5000,"mp3":300})

方法二：
从Python2.2版本开始

>>>fdict=dict((["www","www.linuxeye.com"],["blog","blog.linuxeye.com"])) >>>fdict {"blog":"blog.linuxeye.com","www":"www.linuxeye.com"}

方法三：
从Python2.3版本开始,可以用一个很方便的内建方法fromkeys()来创建一个”默认”字典,字典中元素具有相同的值(如果没有给出，默认为None):

>>>fk_dict={}.fromkeys(("a","b"),"LinuxEye") >>>fk_dict {"a":"LinuxEye","b":"LinuxEye"} >>>fk2_dict={}.fromkeys(("yeho","python")) >>>fk2_dict {"python":None,"yeho":None} >>>fk3_dict={}.fromkeys("yeho","python") >>>fk3_dict {"y":"python","h":"python","e":"python","o":"python"}

Python字典查、增、删、改

>>>product_dict={"MAC":8000,"Iphone":5000,"mp3":300} >>>product_dict["Iphone"] 5000 >>>product_dict["ipad"]=4000#增 >>>product_dict {"ipad":4000,"MAC":8000,"Iphone":5000,"mp3":300} >>>product_dict.keys()#查看索引 ["ipad","MAC","Iphone","mp3"] >>>product_dict.values()#查看值 [4000,8000,5000,300] >>>product_dict.items() [("ipad",4000),("MAC",8000),("Iphone",5000),("mp3",300)] >>>forproduct,priceinproduct_dict.items(): ...printproduct,price ... ipad4000 MAC8000 Iphone5000 mp3300 >>>product_dict.has_key("Iphone")#判断key是否存在 True >>>product_dict.has_key("Itouch") False >>>product_dict.pop("MAC")#删除指定key和value 8000 >>>product_dict {"ipad":4000,"Iphone":5000,"mp3":300} >>>product_dict.popitem()#删除第一个key和value ("ipad",4000) >>>product_dict {"Iphone":5000,"mp3":300} >>>product_dict={"Iphone":5000,"mp3":300} >>>delproduct_dict["Iphone"]#用del函数删除指定key和value >>>product_dict {"mp3":300} >>>product_dict["mp3"]=299#改 >>>product_dict {"mp3":299} >>>product_dict.clear()#清空字典内容（空字典） >>>product_dict {} >>>delproduct_dict#删除字典 >>>product_dict={"mp3":300} >>>delproduct_dict#已删除报错 Traceback(mostrecentcalllast): File"<stdin>",line1,in<module> NameError:name"product_dict"isnotdefined

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