Basic operations of dict and set

dict Three methods of expanding dictionary in

1 The first is direct use key=value

2 Second use setdefault

3 Use update

Two dict Get all the key, Get all value, Get all items

keys

values

items

 

Three definition empty set

 6set in , Difference set , Collection , Find the intersection

Difference set

  Collection

 

intersection

  Four Add an element

use set.add

  Delete an element

 

5、 ... and dict and list in copy Method drawing and code explanation

list——date1=list——date2 It's equivalent to a direct assignment Changing one of them will affect the other

and list——date3 and list——date4 It is a slice copy that changes one without affecting the other

 

dict Shallow copy ,dict_data1 and dict_data2 The two are independent , But the elements inside point to the same , So after a change , The other will change with it

 

 

dict Deep copy, full copy , They are completely independent , Even if you change one , The other remains the same