Python Base---Collection

Set: A mutable data type in which the elements inside must be immutable data types, unordered, and not duplicated. {}

1Set1 = Set ({})2 Print(Set1)3 4 #Add Add,update5Set1 = {'Alex','Wusir','Ritian','Egon','Barry'}6Set1.add ('Goddess')7 Print(Set1)#unordered8 #{' goddess ', ' Egon ', ' Barry ', ' Wusir ', ' Alex ', ' Ritian '}9 TenSet1.update ('Male Gods')#The iteration is incremented, which is equivalent to the extend in the list, by the object one by one plus One Print(Set1) A #{' Male ', ' goddess ', ' Egon ', ' Barry ', ' Wusir ', ' Alex ', ' God ', ' Ritian '} -  - #Delete Pop,remove,del, clear theSet1.pop ()#random Delete, with return value - Print(Set1) -  -Set1.remove ('Elements')#Delete by Element + Print(Set1) -  +Set1.clear ()#emptying the collection A Print(Set1) at  - delSet1#Delete Collection - Print(Set1) -  - #Check -  forIinchSet1: in     Print(i)

Intersection &

The collection |

Difference Set-

Inverse intersection ^

  
 1  set1 = {1,2,3  2  Set2 = {1,2,3,4,5,6}  3  4   Print  (set1 < Set2)  5  print  (Set1.issubset (Set2)) #   These two are the same, both of which illustrate that Set1 is a subset of Set2.  6  7   Print  (set2 > Set1)  8  print  (Set2.issuperset (Set1)) #   These two are the same, both of which illustrate that Set2 is a set1 superset. 

The set is mutable, the element is immutable, and the Frozenset becomes a set invariant

1 s = frozenset ('Barry')2print(S,type (s) ) 3  for inch S: 4     Print (i)

Depth copy

1 #赋值运算 2 l1 = [3] L2 = L14 l1.append ('a'  )5print("{}\t\t{}". Format (L1,L2))  6#[1, 2, 3, ' a ']        [1, 2, 3, ' a ']

1 #浅copy2L1 = [A]3L2 =l1.copy ()4 Print(L1,L2)5 Print(ID (L1), id (L2))6L2.append ('a')7 Print(L1,L2)8 """9 [1, 2, 3] [1, 2, 3]Ten 1848031189768 1848031187272 One [1, 2, 3] [1, 2, 3, ' a '] A """

1L1 = [1,2,[4,5,6],3]2L2 =l1.copy ()3 Print(L1,id (L1))4 Print(L2,id (L2))5L1.append ('a')6 Print(L1,L2)7L1[2].append ('a')8 Print(L1,L2)9 Print(ID (l1[2]))Ten Print(ID (l2[2])) One """ A [1, 2, [4, 5, 6], 3] 2318104334664 - [1, 2, [4, 5, 6], 3] 2318103951432 - [1, 2, [4, 5, 6], 3, ' a '] [1, 2, [4, 5, 6], 3] the [1, 2, [4, 5, 6, ' a '], 3, ' a '] [1, 2, [4, 5, 6, ' a '], 3] - 2318104337160 - 2318104337160 -  + """

For shallow copy, the first layer creates a new memory address, and from the second level it points to the same memory address, so consistency is maintained for the second layer and the deeper layers.

Deep copy

1 ImportCopy2L1 = [1,2,[4,5,6],3]3L2 =copy.deepcopy (L1)4 Print(L1,id (L1))5 Print(L2,id (L2))6L1[2].append ('a')7 Print(L1,L2)8 9L1 = [1,[1],2,3,4]TenL2 =l1[:] OneL1[1].append ('a') A  - Print(L1,id (L1)) - Print(L2,id (L2))

For deep copy, the two are completely independent, changing any element of any one (no matter how many layers), and the other absolutely does not change.

Python Base---Collection