First, Dictionary
1, the dictionary representation
Dictionary definition: by {} are represented Dictionary
Each data dictionary is composed of a key-value pair Key: value , each key-value pairs separated by a comma
Dictionary key is unique (not repeated)
key only immutable data type (recommended key entire string)
key corresponding value value can be any data type
2, the dictionary of additions and deletions to change search
(1) add an element
By direct assignment key, you can increase the element
dic={"name":'xiaoming',"age":12}
dic["height"]=1.70
update method
Add multiple elements
(2) modify the element
Modified by a value corresponding to the specified key
dic["height"]=1.8
(3) Find the elements
Find the key corresponding to the key values, if there is no error will
print(dic[‘aa’])
get method
Find the key values corresponding to the key, if the key does not exist, returns None
dic={"aa":11,"bb":22,"cc":33}
print(dic.get("aa"))
keys method
Gets a dictionary of all the key
print (list (dic.keys ()) ) # to get into a list of key
value method
Get all the values in the dictionary
print(list(dic.values()))
items Methods
Get all the key-value pairs
print(list(dic.items()))
(4) remove elements
pop method
Delete the specified key by key pair
dic={"aa":11,"bb":22,"cc":33}
dic.pop("aa")
print(dic)
popitem method
Delete the last key-value dictionary of ( 3.5 before randomly delete key-value pairs contained 3.5 )
dic.popitem ()
clear method
Empty dictionary
Second, the collection
1, the representation of the set
Defining a set of: by {} expressed
Define an empty set: The set keywords
set1=set()
print(type(set1))
Data set is a variable type
2, a collection of properties
(1) the set of non-duplicate element (for a list of fast de-emphasis)
(2) only the set of data stored immutable type (variable type and hard type for distinguishing data)
The definition of a collection, put the data collection will not be seen in error