Python集合set的用法
阿新 • • 發佈:2018-12-15
建立集合(括號中只能有一個引數):
>>> s = set('set')
>>> s
{'s', 't', 'e'}
>>> s = set(['set'])
>>> s
{'set'}
增加一個元素:
>>> s
{'set'}
>>> s.add('python')
>>> s
{'set', 'python'}
增加多個元素(求並集):
>>> s {'set', 'python'} >>> s.update('py') >>> s {'y', 'p', 'set', 'python'} >>> s.update(['py','st']) >>> s {'y', 'p', 'py', 'st', 'python', 'set'}
刪除一個元素:
>>> s
{'y', 'p', 'py', 'st', 'python', 'set'}
>>> s.remove('st')
>>> s
{'y', 'p', 'py', 'python', 'set'}
求交集:
>>> a = set([1,2,3])
>>> b = set([2,3,4])
>>> a & b
{2, 3}
求並集:
>>> a | b
{1, 2, 3, 4}
求差集:
>>> a - b {1} >>> b - a {4}
集合是無序的,也不能對其進行索引或切片:
>>> a[0] Traceback (most recent call last): File "<pyshell#42>", line 1, in <module> a[0] TypeError: 'set' object does not support indexing >>> a[:] Traceback (most recent call last): File "<pyshell#43>", line 1, in <module> a[:] TypeError: 'set' object is not subscriptable