Python中的字典的定义以及案例

1 alien={'color':'blue','point':6}#the definition of dictionary
2 #in python ,dictionary is represented by a series of key-value pairs place in {}
3 print(alien['color'])#print the value of color
4 #from this example,we can find the way to receive the appointed value from dictionary
5 value_color=alien['color']6 value_point=alien['point']7 print(f"your face is {value_color}")#using variables in strings
8 print(f"your face is {value_color},and have {value_point} buttons in your clothes")9 #modify the value in key-value pairs is the same of C,you just overwrite the old value with new values
10 del alien['color']11 print(alien)12 alien['age']=16
13 alien['leg']=5
14 value_mother=alien.get('mother','no mother values assigned')15 #if the value of mother is not assgned,it will print'no mother values assigned',rather show error
16 print(value_mother)17 value_age=alien.get('age','no age values assigned')18 print(value_age)19 #from this example ,we can find if we can not sure there is the appointed value in dictionary,we should consider using .get() firstly

1 #We have already know the traversal in Python,the first example is tell this.
2 favorite_fruit={3     'Tom':'banana',4     'Jack':'apple',5     'Kim':'strawberry',6     'Limin':'grapefruit'
7 }8 for name,fruit infavorite_fruit.items():9     print(f"\nName:{name}")10     print(f"Fruit:{fruit}")11 #now,we have one question for whether we could get the key only or just get value
12 #in order to meet the above needs,we should use .key() method
13 print("\n")14 Good_Students=['Jack','Kim']15 '''
16 (solution 1)if 'Fu' not in favorite_fruit.keys():17 print("Fu,please tell me waht fruit you like")18         '''
19 for name infavorite_fruit.keys():20     print(name.title())21     if name inGood_Students:22         fruit=favorite_fruit[name].title()#get the specified value
23         print(f"\t {name.title()},i know you like {fruit}")#the same meaning
24     if 'Fu' not infavorite_fruit.keys():25         print("Fu,please tell me waht fruit you like")26         '''
27 #if the code is set in this place ,we will find it will be print many times!28 #so,we need one solution to solve it29 #for instance,we can adjust the place the code is30 (solution 2)if 'Fu' not in favorite_fruit.keys():31 #print("Fu,please tell me waht fruit you like")32         '''
33 #we have solved the above problem,so why not try to traversal the value?
34 print("there are many kinds of fruit that student like\n")35 for fruits infavorite_fruit.values():36     print(fruits.title())37     #find the fruit which initials is A
38     if(fruits[:1].title()=='A'):39         print("\t the fruit's initials is A")40 #however,if there are many duplicate values in the set,that means the program will do useless work
41 #To solve the problem,we can use .set()
42 for fruits inset(favorite_fruit.values()):43     print(fruits.title())44     #find the fruit which initials is A
45     if(fruits[:1].title()=='A'):46         print("\t the fruit's initials is A")47 #the result is not change
48 #now,we have another question,we have find the way to get values through keys,so,could we find the keys through values?
49 #the answer is Yes,we still ues the same code,and add some new code above the original code
50 defget_key(key,value):51     return [r_key for (r_key,r_value) in key.items() if r_value==value]52 for fruits infavorite_fruit.values():53     print(fruits.title())54     #find the fruit which initials is A
55     if(fruits[:1].title()=='A'):56         find_value=fruits57         goal_key=get_key(favorite_fruit,find_value)58         final_key=goal_key[0]#the value is stored in list
59         print(f"\t {final_key} is the goal keys")