Python: set实例透析

a = set([1,2,3,1])
b = set([2,3,4])

a

{1, 2, 3}

print b

set([2, 3, 4])

a

{1, 2, 3}

len(a)

3

2 in a

True

# 像遍历字典一样
for i in a:
    print i,

1 2 3

a.add(4)

a

{1, 2, 3, 4}

# a.remove(el), if not found, raise error
a.remove(4)

a

{1, 2, 3}

# a.discard(el), if not found, do nothing
a.discard(4)

a.pop()

1

a

{2, 3}

a.intersection(b)

{2, 3}

# a - b
a.difference(b)

set()

# b - a
b.difference(a)

{4}

a.issubset(b)

True

b.issuperset(a)

True

a.clear()

a

set()