[4-1] Notes Python language foundation - a collection set

set

　　Only store immutable objects

　　Objects are unordered

　　Can not be duplicated elements

Create Collection

s = {12, 32, 5436, 2, 44}
s2 = set({1, 2, 346, 7, 8})

in 和 not in

len (s1)

Adding elements

　　s1.add() 

　　s1.update(s2)

delete

　　s1.pop () removes an element of random

　　s1.remove (12) to delete the specified element

　　s1.clear () empty set

copy () shallow copy

Collection operation

　　& Intersection

　　| Union

　　- Set difference result = s1 - s2

　　^ Or will set

　　<= Child Collection

　　<Mako Collection