python学习之集合

集合（set）是一个无序的不重复元素序列。

可以使用大括号 { } 或者 set() 函数创建集合，注意：创建一个空集合必须用 set() 而不是 { }，因为 { } 是用来创建一个空字典。

创建格式：

parame = {value01,value02,...}
或者
set(value)

1、add（增加元素）

name = set(['Tom','Lucy','Ben'])
name.add('Juny')
print(name)

#输出：{'Lucy', 'Juny', 'Ben', 'Tom'}

name = set(['Tom','Lucy','Ben'])
name.clear()
print(name)

#输出：set()

name = set(['Tom','Lucy','Ben'])
new_name = name.copy()
print(new_name)

#输出：{'Tom', 'Lucy', 'Ben'}

A = set([2,3,4,5])
B = set([3,4])
C = set([2])
n = A.difference(B,C)
print(n)

#输出：{5}
#返回A集合里面，在B和C集合中没有的元素，并生成新的集合

A = set([2,3,4,5])
B = set([4,5])
A.difference_update(B)
print(A)

#输出：{2, 3}

n = set([2,3,4])
n.discard(3)
print(n)

#输出：{2, 4}

n1 = set([2,3,4,5])
n2 = set([4,5,6,7])
n = n1.intersection(n2)
print(n)

#输出：{4, 5}

n1 = set([2,3,4,5])
n2 = set([4,5,6,7])
n1.intersection_update(n2)
print(n1)

#输出：{4, 5}

n1 = set([2,3,4,5])
n2 = set([4,5,6,7])
print(n1.isdisjoint(n2))

#输出：False

A = set([2,3])
B = set([2,3,4,5])
print(A.issubset(B))

#输出：True
#A是B的子集

A = set([2,3])
B = set([2,3,4,5])
print(B.issuperset(A))

# 输出：True
#B是A的父集

n = set([2,3,4,5])
n1 = n.pop()
print(n,n1)

# 输出：{3, 4, 5} 2

n = set([2,3,4,5])
n.remove(2)
print(n)

# 输出：{3, 4, 5}

A = set([2,3,4,5])
B = set([4,5,6,7])
print(A.symmetric_difference(B))

# 输出：{2, 3, 6, 7}

A = set([2,3,4,5])
B = set([4,5,6,7])
A.symmetric_difference_update(B)
print(A)

# 输出：{2, 3, 6, 7}

A = set([2,3,4,5])
B = set([4,5,6,7])
print(A.union(B))

# 输出：{2, 3, 4, 5, 6, 7}

A = set([2,3,4,5])
B = set([4,5,6,7])
A.update(B)
print(A)

# 输出：{2, 3, 4, 5, 6, 7}