Pythonのセット操作

参考

https://www.amazon.co.jp/パーフェクトPython-PERFECT-5-Pythonサポーターズ/dp/477415539X

要素の追加削除

discardは該当要素がなくても例外発生しない

>>> a = {1,2,3,4,5}
>>> a.add(6)
>>> a
{1, 2, 3, 4, 5, 6}
>>> a.remove(3)
>>> a
{1, 2, 4, 5, 6}
>>> a.remove(7)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 7
>>> a
{1, 2, 4, 5, 6}
>>> a.discard(7)
>>> a
{1, 2, 4, 5, 6}
>>> a.discard(1)
>>> a
{2, 4, 5, 6}
>>> 

合併

>>> a = {1,2}
>>> b = {1,3}
>>> c = {1,4}
>>> a | b | c
{1, 2, 3, 4}
>>> 

共通要素の抽出

>>> a
{1, 2}
>>> b
{1, 3}
>>> c
{1, 4}
>>> a & b & c
{1}
>>> 

差の抽出

>>> a
{1, 2}
>>> b
{1, 3}
>>> c
{1, 4}
>>> a - b - c
{2}
>>>

独自要素の抽出

>>> a
{1, 2}
>>> b
{1, 3}
>>> c
{1, 4}
>>> a ^ b
{2, 3}
>>> a ^ b ^ c
{1, 2, 3, 4}
>>> a ^ (b | c)
{2, 3, 4}
>>> 

要素の全てを含んでいるか確認

>>> a
{1, 2}
>>> b
{1, 2, 3}
>>> c
{2, 4}
>>> a <= b
True
>>> a <= c
False
>>> b >= a
True
>>> b >= c
False
>>>