자료구조 : Set

set

• set
  SET can't have duplicate values
  SET elements don't have index(order)

• set 생성
  using set() function

  Ex.

  ```
  my_set = set()
  my_set = set([1, 2, 3, 4, 5, 1, 2, 3, 4, 5])
  my_set = set((1, 2, 3, 4, 5, 1, 2, 3, 4, 5))
  # my_set = {1, 2, 3, 4, 5}
  ```

• 값 추가
  - add(obj) : add an element whose value is 'obj' in that set
  - update({obj, ...}) : add {obj, ...} in that set

  Ex.

  ```
  my_set = set()
  my_set.add(1)
  my_set.add(2)
  my_set.add(3)
  # my_set = {1, 2, 3}
  ##################################3
  my_set.update({4, 5, 6})
  # my_set = {1, 2, 3, 4, 5, 6}
  ```

• 값 삭제
  - remove(obj) : remove an element whose value is obj in that set (SET doesn't have index, so you can't use del(), pop() function)

  Ex.

  ```
  my_set.remove(5)
  # my_set = {1, 2, 3, 4, 6}
  ```

• 집합 함수
  - 교집합 : intersection() / &
  - 합집합 : union() / |
  - 차집합 : difference() / -

  Ex.

  ```
  a = {1, 2, 3, 4, 5}
  b = {3, 4, 5, 6, 7}
  # 교집합
  print(a & b)
  print(a.intersection(b))
  #합집합
  print(a | b)
  print(a.union(b))
  #차집합
  print(a - b)
  print(a.difference(b))
  ```

  ㄴ> 출력 값

  ```
  {3, 4, 5}
  {3, 4, 5}
  {1, 2, 3, 4, 5, 6, 7}
  {1, 2, 3, 4, 5, 6, 7}
  {1, 2}
  {1, 2}
  ```