Learning Python (vi) dictionary collection

1, the dictionary

It helps users to information indicating a thing (thing that have multiple attributes)

Another variable is the dictionary container model, and can store any type of object. (Random arrangement)

Each dictionary key (key => value) of the colon ( : ) is divided, with between each pair comma ( , ) is divided, in the entire dictionary including curly braces ( {}) in the following format:

d = {key1 : value1, key2 : value2 }

Key must be unique, but the value is not necessary.

Value may take any data type, but the key must be immutable, such as strings, numbers, or tuples.

A simple example dictionary:

dict = {'Alice': '2341', 'Beth': '9102', 'Cecil': '3258'}

So also create a dictionary:

dict1 = { 'abc': 456 }
dict2 = { 'abc': 123, 98.6: 37 }

Unique features:

= {info ' name ' : ' John Doe ' , ' Age ' : 28, ' Gender ' : ' M ' , ' Hoppy ' : ' basketball ' }

keys: Gets a dictionary of all the key

Print (info.keys ()) # Get the dictionary all bonds dict_keys ([ 'name', ' age', 'gender', 'hoppy'])

for item in info.keys():
    print(item)

values: Get all the values in the dictionary

Print (info.values ()) # Get all the values dict_values dictionary ([ 'Joe Smith', 28, 'M', 'basketball'])

for item in info.values():
    print(item)

items: Gets a dictionary of all the key-value pairs

Print (info.items ()) # Get all key-value pairs in the dictionary dict_items ([( 'name', ' John Doe'), ( 'age', 28), ( 'gender', ' M'), ( 'hoppy', 'basketball')])

v1 for, v2 in info.items (): # key will be assigned to v1 v2
    print(v1,v2)

get: to determine whether there is a dictionary key, without the creation

information = [ ' k1 ' : ' v1 ' , ' k2 ' : ' v2 ' ]

v1 = info [ ' K3 ' ]
V2 = info. GET ( ' K3 ' ) in Python is empty #none
v3 = info.get('k3'，666)
print（）

#None data type that represents an empty (no functional, specifically for providing null)

pop / del: Delete

the info = { ' k1 ' : ' v1 ' , ' k2 ' : ' v2 ' }
result = info.pop('k2')
print(info,result)

del info [ ' k1 ' ]
 print (info)

update: do not exist, add; there is, then update

the info = { ' k1 ' : ' v1 ' , ' k2 ' : ' v2 ' }

# Does not exist, add; exist, updating 
info.update ({ ' K3 ' : ' V3 ' , ' K4 ' : ' V4 ' , ' K2 ' : 666 })
 Print (info)

Exercises:

dict_ = {'name':'alex','password':'oldboy'}
User = INPUT ( ' User: ' )
pwd = INPUT ( ' password: ' )

if user == dict_['name'] and pwd ==dict_['password']:
    print('ok')
else:
    print('No')