Python set of characteristics, the conventional method of application scenarios and

1. The basic concept set

1.1 non-repeatable set of elements inside

s = {1, 1, 1, 1, 1, 3, 5, 67, 89}
print(s,type(s))

Output:

1.2 Definitions an empty set

s1 = {}
print(type(s1))  # 默认情况下是dict
s2 = set([])     # 定义一个空集合
print(s2,type(s2))

Output:

2. Characteristics of the collection

Collection supports only member operators, for loop

2.1 member operator

s = {1,2,3}
print(1 in s)
print(1 not in s)

Output:

2.2 for loop

s = {1,2,3}
for i in s:
    print(i,end='')
print()

Output:

3. The method set common

Add 3.1

A set of variable data type is
added sequentially and the order of storage is not the same

s = {4,5,6,7,8,9,2}
print(s)

#添加一个元素s.add()
s.add(10)
s.add(0)
print(s)

#添加多个元素a.update()
s.update({3,6,7,8})
print(s)

Output:

3.2 Delete

s = {4,5,6,7,8,9,2}
a = s.pop()
print(s)
print(a)

# 删除指定的元素
s.remove(9)
print(s)

Output:

3.3 Sorting

s1 = {2,3,1}
sorted(s1)
print(s1)

Output:

3.4 union

s1 = {2,3,1}
s2 = {2,3,4}
print('并集:',s1.union(s2))
print('并集:',s1 | s2)

Output:

3.5 Intersection

s1 = {2,3,1}
s2 = {2,3,4}
print('交集:',s1.intersection(s2))
print('交集:',s1 & s2)

Output:

3.6 difference set

difference set s1 and s2: s2, which elements have not s1

s1 = {2,3,1}
s2 = {2,3,4}
print('差集:',s1.difference(s2))
print('差集:',s1 -s2)

Output:

3.7 pairs of differential, etc.

Peer difference: the union - intersection

s1 = {2,3,1}
s2 = {2,3,4}
print('对等差分:',s1.symmetric_difference(s2))
print('对等差分:',s1 ^ s2)

Output:

3.8 judge

s1.issubset(s2): S1 s2 whether a subset of
s1.isdisjoint(s2): Two sets are not disjoint

s1 = {'westos','redhat','python'}
s2 = {'redhat','westos','linux'}
# s1是否是s2的子集
print(s1.issubset(s2))
# 两个集合是不是不相交
print(s1.isdisjoint(s2))

Output:

4. The set of scenarios

Quick to re-list

li = [1,2,3,4,5,6,6,6,7,8,9,9,9]
print(list(set(li)))

Output: