Actions for the Python collection

two major features of the collection:

First, to Heavy

Second, the relationship test

1, to the effect of weight

>>> L1 = ["Zhang San", "John Doe", "Harry", "Zhang San"]

>>> print (Type (L1))//view type

<class ' list ' >

>>> L1 = set (L1)//set the list into a collection

>>> Print (L1)

{' John Doe ', ' Zhang San ', ' Harry '}

>>> print (Type (L1))

<class ' Set ' >

2, take the intersection of two sets

>>> L1 = set ([1,2,3,4,5])

>>> L2 = Set ([1,6,7,8,9])

>>> Print (L1.intersection (L2))//intersection is the intersection meaning, the intersection of two lists is "1"

{1}

3, take the set of two sets

>>> L1 = set ([1,2,3,4,5])

>>> L2 = Set ([1,6,7,8,9])

>>> Print (L1.union (L2))//union is the meaning of the Union, that is, two of the list after merging to the weight

{1, 2, 3, 4, 5, 6, 7, 8, 9}

4, take two sets of difference set

>>> Print (L1.difference (L2))//That is L1 has, L2 not the element

{2, 3, 4, 5}

>>> Print (l2.difference (L1))//l2 There are elements that are not L1

{8, 9, 6, 7}

5, judge the subset and the parent set, that is to judge whether it contains the relationship

>>> L3 = Set ([2,3,4])

The elements in the >>> print (L3.issubset (L1))//l1 contain elements from L3, so L3 is a subset of L1

True

>>> Print (L3.issubset (L2))

False

>>> Print (L1.issuperset (L3))//L1 is the parent set of L3

True

6, take out two sets of symmetric difference sets, that is, two sets of non-existent elements of each other

>>> L1

{1, 2, 3, 4, 5}

>>> L2

{1, 6, 7, 8, 9}

>>> Print (L1.symmetric_difference (L2))//two sets in addition to element "1", each other does not exist

{2, 3, 4, 5, 6, 7, 8, 9}

You can also use operators to complete the above operations

1. Intersection:

>>> print (L1 & L2)

{1}

2, and set

>>> Print (L1 | l2)

{1, 2, 3, 4, 5, 6, 7, 8, 9}

3. Difference Set

>>> Print (L1-L2)

{2, 3, 4, 5}

4. Symmetrical difference Set

>>> print (L1 ^ L2)

{2, 3, 4, 5, 6, 7, 8, 9}

Collection additions and deletions change

1. Adding a collection element

>>> L1.add (666)//Add a single element using the add

>>> Print (L1)

{1, 2, 3, 4, 5, 666}

>>> l1.update ([777,888,999])//update method can add multiple elements at the same time

>>> Print (L1)

{1, 2, 3, 4, 5, 999, 777, 888, 666}

2. Deleting collection elements

>>> L1.remove (666)

>>> Print (L1)

{1, 2, 3, 4, 5, 999, 777, 888}

Actions for the Python collection