Python day two-basic use of dictionary types explained

Students who have studied Java know that there is a data format for key-value pairs in Java--map

In Python, there is a format similar to map, which is the dictionary (Dict)

1. Create a Dictionary type Object

user={    "username":"Dylan",     "  Age ":",    "password":"123" }

2. Traverse

User={    "username":"Dylan",    " Age":" -",    "Password":"123"} forKvinchUser.items ():Print(k +":"+V);

Results: Username:dylan
Age:18
Password:123

3.Clear () method--Clears all elements in the dictionary

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }user.clear ();  print  (user); 

The result is:{}

4.Copy () copies one part into another dictionary

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }user2  =user.copy ();  print  (user2); 

Result:{' password ': ' 123 ', ' username ': ' Dylan ', ' age ': ' + '}

5.Fromkeys(): Do not preserve the value of the source dictionary, create a new dictionary

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }user2  =dict.fromkeys (user);  print  (user2); 

Result:{' username ': none, ' age ': none, ' Password ': none}

6.Get(): Get the value by key

User={    "username":"Dylan",    " Age":" -",    "Password":"123"}username=user.get ("username");Print(username);

Results:Dylan

7. Items (): Get all the entries for the dictionary (item)

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }arr  =user.items ();  print  (arr); 

Results:dict_items ([' Age ', ' + '), (' username ', ' Dylan '), (' Password ', ' 123 ')])

8.keys(): Get all keys

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }arr  =user.keys ();  print  (arr); 

Results:dict_keys ([' username ', ' password ', ' age '])

9.Pop(): Removes the item item of the specified key

User={    "username":"Dylan",    " Age":" -",    "Password":"123"}user.pop (" Age");Print(user);

Result:{' password ': ' 123 ', ' username ': ' Dylan '}

10. Popitem ()-Removes the first item in a dictionary

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }user.popitem ();  print  (user); 

Result:{' age ': ' + ', ' password ': ' 123 '}

Items(): Get all the values of the dictionary

 user={  "  Username   ": "   Dylan   "   " age  " :  " 18  "   ,   password  " :  " 123  "  }values  =user.values ();  print  (values); 

Results:dict_values (['], ' Dylan ', ' 123 ')

del keyword-deletes the specified item according to the specified key

User={    "username":"Dylan",    " Age":" -",    "Password":"123"}deluser["username"]Print(user);

Result:{' age ': ' + ', ' password ': ' 123 '}

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I will soon fall down, but will tell me, perseverance is victory, I work until the sun to see tomorrow!

Python day two-basic use of dictionary types explained