## 1.Method for creating a set

`````` 1)s={1,"python"}
2)s=set("python") or s=set([1,"python"])
ps. set to list:
lst=list(s)
list to set(can remove duplicate elements from the set):
s=set([1,"python"])
Create an immutable set in "frozenset"
``````

## 2.Common method of set

`````` 1)add
eg.
b=set()
2)update
eg.
>>>setb={"python",(1,2,3)}
>>>seta.update(b)
>>>seta
3)pop
eg.
>>>seta.pop()#Random deletion of an element
4)remove
eg.
>>>seta.remove("wiki")#delete the element，If it does not exist, it will be reported to the wrong
eg.
>>>seta.discard("wiki")#If it does not exist, it will not be reported to the wrong
6)clear
eg.
>>>seta.clear()
>>>seta
set([])
``````

## 3.Operations With Set

`````` 1)To determine whether an element is in the set.
eg.
>>> s = set([1,2,3,4])
>>> 1 in s
True
>>> 5 in s
False
2)Judge whether the two sets are equal.
eg.
>>> a = set([1,2,3,4,5])
>>> b = set([1,2,3,4,5])
>>> a ==b
True
>>>b.pop()
1
>>>b
set([2,3,4,5])
>>>a==b
False
3)To determine whether a subset
eg.
>>> a = set([1,2,3,4])
>>> b = set([1,2,3,4,5])
>>>a < b
True
>>>a.issubset(b)
True
4)To determine whether a superset
eg.
>>> a = set([1,2,3,4])
>>> b = set([1,2,3,4,5])
>>>b > a
True
>>>b.issuperset(a)
True
5)To get the union set
eg.
>>> a = set([0,1,3,4,6])
>>> b = set([1,2,3,4,5])
>>> a | b
set([0,1,2,3,4,5,6])
>>> a.union(b)
set([0,1,2,3,4,5,6])
6)To get the intersection
eg.
>>> a = set([0,1,3,4,6])
>>> b = set([1,2,3,4,5])
>>> a & b
set([1,3,4])
>>> a.intersection(b)
set([1,3,4])
7)To get the difference for the other set
eg.
>>> a = set([0,1,3,4,6])
>>> b = set([1,2,3,4,5])
>>> a - b
set([0,6])
>>> a.difference(b)
set([0,6])
8)To get the union of difference sets
eg.
>>> a = set([0,1,3,4,6])
>>> b = set([1,2,3,4,5])
>>> a.symmetric_difference(b)
set([0,6,2,5])
``````

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