假設：目前已在字典dict_stu，它的定義如下：

dict_stu = {
"171001":{
"name":"xiaohua",
"age":21,
"sex":'g',
},
"171002":{
"name":"xiaoli",
"age":21,
"sex":'g',
},
}

字典常用的方法包含：

　　1、增加key-value；通過dict_stu[key_new]={value_new};? 通過dict_stu.update(dict_new);??

　　2、修改某個key對應的value；通過dict_stu[key_modify]={values_new}

　　3、查找某個key對應的value；通過dict_stu[key_find];? 通過dict_stu.get(key_find);? 通過dict_stu.setdefault(key_find,"defualt value");?

　　3.1、返回字典中所有的值；通過dict_stu.values()

　　4、刪除某個key對應的value；通過del dict_stu[key_del]; 通過dict_stu.pop(key_del);??

　　5、復制一個字典：通過dict_stu.copy()

　　6、判斷字典key是否在字典中：通過key in dict_stu;? 通過key not in dict_stu

　　7、計算字典的長度：通過len(dict_stu)

　　8、創建一個（不）含默認值的字典：dict.fromkeys(key_list,values)

　　9、刪除整個字典：通過del dict_stu;? 通過dict_stu.clear()

測試示例：

#author FK dict_stu = { "171001":{ "name":"xiaohua", "age":21, "sex":'g', }, "171002":{ "name":"xiaoli", "age":21, "sex":'g', }, } new_stu = { "171008":{ "name":"lili", "age":23, "sex":'g', }, "171002":{ "name":"lulu", "age":20, "sex":'g', } } #增加或修改字典中的數據，如果沒有對應的key便增加，如果有對應的key便修改;dict insert data dict_stu["171003"]={ "name":"xiaoliang", "age":22, "sex":'m', } #返回字典的成員個數;return the number of items in the dictionary print("after add item.the length of dict is:",len(dict_stu)) #刪除字典某個key的成員，如果沒有key拋出異常;remove dict_stu[key] from dict,Raises a KeyError if key is not in the map del dict_stu["171003"] #返回并刪除字典中某個key的值或default，如果key存在返回key對應的值，如果key不存在，設置了default則返回defalut值，如果沒設置則報錯 print("\033[31;1mtest the pop method:\033[0m",dict_stu.pop("171002")) #pop方法沒有設置default，測試報錯 #print("\033[31;1mtest the pop method,there is no 171002 key\033[0m",dict_stu.pop("171002")) #pop方法有設置default，測試正常 print("\033[31;1mtest the pop method,there is no 171002 key:\033[0m",dict_stu.pop("171002","the default is defined")) #return the number of items in the dictionary print("after del item.the length of dict is:",len(dict_stu)) #測試key是否在字典中,如果存在返回true ,同key not in d;retrun True if dict_stu has a key 'key' ,else False print("\033[31;1mtest the 171003 is the dict_stu's key?\033[0m","171003" in dict_stu) #返回字典中key對應的value,如何沒有返回None;retrun the value for key if key is in the dictionary,else default return None print("return the 171001's values:",dict_stu.get("171001")) #如果key在字典中,返回字典中key對應的value;如果key沒有在字典中,返回默認值 print("\033[31;1msetdefault methord return the 171001's values:\033[0m",dict_stu.setdefault("171001","default values")) print("\033[41;1msetdefault methord return the 171008's values:\033[0m",dict_stu.setdefault("171008","default values")) #方法1:升級一個字典;update the dictionary dict_stu.update(new_stu) print("\033[21;1muse update method update the dict_stu:\033[0m",dict_stu) #字典的淺復制 dict_copy = dict_stu.copy(); print("\033[41;1mthe copy of the dict_stu\033[0m",dict_copy) print("test the copy dict is equle the org dict:",dict_copy == dict_stu) print("the dict of dict_stu",dict_stu) #return a new view of the dictionary's values print("\nthe dict_stu.values methord:\t",dict_stu.values()) #創建一個字典通過fromkeys方法,以序列seq中元素做字典的鍵，value為字典所有鍵對應的初始值 dict1_fromkeys = dict.fromkeys([1,2,3,4],50) dict2_fromkeys = dict.fromkeys([1,2,3,4],[50,20,10,79]) dict3_fromkeys = dict.fromkeys([1,2,3,4],set([50,20,10,79])) print("\033[31;1mcreate a dict with keys from seq and values set\033[0m",dict1_fromkeys) print("\033[31;1mcreate a dict with keys from seq and values set\033[0m",dict2_fromkeys) print("\033[31;1mcreate a dict with keys from seq and values set\033[0m",dict3_fromkeys) dict1_fromkeys[1]="修改" #由于是淺復制，所以修改列表中的一個元組，其它節點就都修改了 dict2_fromkeys[1][0]="90" print("\033[31;1mmodify the dict with keys from seq and values set\033[0m",dict1_fromkeys) print("\033[31;1mmodify the dict with keys from seq and values set\033[0m",dict2_fromkeys) #返回字典中所有的值 print("return a new view of the dictionary's values:",dict_stu.values()) #remove all items from the dictionary dict_stu.clear() print("after clear the dict is:",dict_stu)

轉載于:https://www.cnblogs.com/fkblogmx/p/7825805.html

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