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Python集合

从未止步.. 人气:0

集合的创建

使用内置函数set()进行转化或者使用{}包括起来的,集合中的元素:无序性,互异性,确定性。

举例:

numbers=set(range(0,7))//使用内置函数进行转化
print(numbers)
print(type(numbers))

输出:

{0, 1, 2, 3, 4, 5, 6}
<class 'set'>

互异性

fruit={'apple','orange','banana',"apple",'apple','orange','banana',"apple"}
print(fruit)
print(type(fruit))

输出:

{'apple', 'banana', 'orange'}
<class 'set'>

无序性

集合中的元素不能通过下标访问。

举例:

fruit =set({'apple',9,"axn","dbu",12})
print(fruit[2])

集合中的操作函数

在集合中添加元素

add() 函数

举例:

fruit =set({'apple',9,"axn","dbu",12})
fruit.add("bc")
print(fruit)

输出:

{'bc', 'apple', 9, 12, 'dbu', 'axn'}

删除集合中的第一个元素

pop()函数

举例:

fruit =set({'apple',9,"axn","dbu",12})
fruit.pop()
print(fruit)

输出:

{'apple', 9, 12, 'axn'}

删除集合中的指定元素

1:remove()函数,若该元素不存在则会报错

举例:

fruit =set({'apple',9,"axn","dbu",12})
fruit.remove("banana")
print(fruit)

fruit =set({'apple',9,"axn","dbu",12,"apple"})
fruit.remove("apple")
print(fruit)

输出:

{'dbu', 'axn', 9, 12}

2:discard()函数,若指定元素不存在不会报错

举例:

fruit =set({'apple',9,"axn","dbu",12,"apple"})
fruit.discard("banana")
print(fruit)

输出:

{'dbu', 'apple', 9, 'axn', 12}

fruit =set({'apple',9,"axn","dbu",12,"apple"})
fruit.discard("apple")
print(fruit)

输出:

{'dbu', 'axn', 9, 12}

判断元素是否在集合里面

if in/not in语句

举例:

fruit =set({'apple',9,"axn","dbu",12,"apple"})
if "apple" in fruit:
    print("yes")
else:
    print("NO")
if "banana" not in fruit:
    print("YES")
else:
    print("NO")

输出:

yes
YES

集合的遍历

for循环

fruit =set({'apple',9,"axn","dbu",12,"apple"})
for i in fruit:
    print(i,end=' ')

输出:

axn 9 apple 12 dbu 

集合元素个数的计算

len()函数

举例:

fruit =set({'apple',9,"axn","dbu",12,"apple"})
print(len(fruit))

输出:

5//注意集合元素的唯一性特征

集合与字典,列表,元组的嵌套

集合与字典:

s1=set({"name":"jason","age":19,"地址":"北京市"})
print(s1)
print(type(s1))

输出:

{'地址', 'name', 'age'}//只输出键名
<class 'set'>

集合与元组

举例:

s1={("name","jason","age",19,"地址","北京市"),12,34,0}
print(s1)
print(type(s1))

输出:

{0, 34, ('name', 'jason', 'age', 19, '地址', '北京市'), 12}
<class 'set'>

使用内置函数进行转化:

s1=set({"name","jason","age",19,"地址","北京市"})
print(s1)
print(type(s1))

输出:

{'age', 'jason', 19, '地址', '北京市', 'name'}
<class 'set'>

集合与列表

举例:

s2=set(["name","jason","age",19,"地址","北京市"])
print(s2)
print(type(s2))

输出:

{'北京市', 'age', 'jason', 19, 'name', '地址'}
<class 'set'>

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