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創(chuàng)新互聯(lián)Python教程：Python之set集合的相關(guān)介紹
認(rèn)識(shí)python中的SET集合及其用法
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python中，集合(set)是一個(gè)無(wú)序排列，可哈希，支持集合關(guān)系測(cè)試,不支持索引和切片操作，沒有特定語(yǔ)法格式，只能通過(guò)工廠函數(shù)創(chuàng)建.集合里不會(huì)出現(xiàn)兩個(gè)相同的元素，所以集合常用來(lái)對(duì)字符串或元組或列表中的元素進(jìn)行去重操作。
生成一個(gè)集合可以使用如下語(yǔ)法：
生成集合語(yǔ)法1：
>>> l1=[1,2,3,4,5,6]
>>> s1=set(l1)
>>> print(s1)
{1, 2, 3, 4, 5, 6}在這里，使用工廠函數(shù)set創(chuàng)建集合，set的參數(shù)可以是一個(gè)列表，也可以是一個(gè)元組或字符串。
生成集合語(yǔ)法2：
>>> s2={6,7,8,9,10}
>>> print(s2)
{8, 9, 10, 6, 7}生成集合語(yǔ)法3：
>>> s3={i for i in range(10)}
>>> print(s3)
{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}集合類型的方法和操作：
add
為集合增加一個(gè)元素，如果集合中本來(lái)已經(jīng)存在這個(gè)元素對(duì)集合無(wú)影響 Add an element to a set. This has no effect if the element is already present.
>>> s1={1,2,3,4,5,6,7}
>>> s1.add(8)
>>> print(s1)
{1, 2, 3, 4, 5, 6, 7, 8}
>>> s1.add(9)
>>> print(s1)
{1, 2, 3, 4, 5, 6, 7, 8, 9}clear
清空集合里所有的元素 Remove all elements from this set.
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9}
>>> s1.clear()
>>> print(s1)
set()
>>> s2.clear()
>>> print(s2)
set()copy
對(duì)集合進(jìn)行淺拷貝(只復(fù)制元素，不復(fù)制內(nèi)存地址) Return a shallow copy of a set.
>>> s1={1,2,3,4,5,6,7}
>>> print(s1,id(s1))
{1, 2, 3, 4, 5, 6, 7} 140509859430472
>>> s2=s1.copy()
>>> print(s2,id(s2))
{1, 2, 3, 4, 5, 6, 7} 140509842716712difference
求兩個(gè)或多個(gè)集合的差集，并返回一個(gè)新集合 Return the difference of two or more sets as a new set.
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s1.difference(s2)
{1, 2, 3, 4}
>>> s2.difference(s1)
{8, 9, 10}difference_update
把兩個(gè)集合的交集部分從集合中移除 Remove all elements of another set from this set.
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s1.difference_update(s2)
>>> print(s1)
{1, 2, 3, 4}
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s2.difference_update(s1)
>>> print(s2)
{8, 9, 10}相關(guān)推薦：《Python視頻教程》
discard
從集合中移除一個(gè)元素，如果被移除的元素不在集合中，不會(huì)報(bào)錯(cuò) Remove an element from a set if it is a member. If the element is not a member, do nothing.
{1, 2, 3, 4, 5, 6, 7}
>>> s1.discard(7)
>>> print(s1)
{1, 2, 3, 4, 5, 6}
>>> s1.discard(4)
>>> print(s1)
{1, 2, 3, 5, 6}
>>> print(s1)
{1, 2, 3, 5, 6}intersection
求兩個(gè)或多個(gè)集合中的交集 Return the intersection of two sets as a new set.
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s1.intersection(s2)
{5, 6, 7}
>>> s2.intersection(s1)
{5, 6, 7}intersection_update
把兩個(gè)集合的交集做為新的集合 Update a set with the intersection of itself and another.
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s1.intersection_update(s2)
>>> print(s1)
{5, 6, 7}
>>> print(s2)
{5, 6, 7, 8, 9, 10}
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s2.intersection_update(s1)
>>> print(s2)
{5, 6, 7}
>>> print(s1)
{1, 2, 3, 4, 5, 6, 7}isdisjoint
兩個(gè)集合沒有交集則返回True Return True if two sets have a null intersection.
>>> s1={1,2,3,4,5,6,7}
>>> s2={5,6,7,8,9,10}
>>> s1.isdisjoint(s2)
False
>>> s1={1,2,3,4}
>>> s2={6,7,8,9}
>>> s1.isdisjoint(s2)
Trueissubset
如果本集合是參數(shù)集合的子集，返回True Report whether another set contains this set.
>>> s1={1,2,3,4}
>>> s2={1,2,3,4,5,6,7}
>>> s1.issubset(s2)
True
>>> s2.issubset(s1)
Falseissuperset
如果本集合是參數(shù)集合的超集，返回True Report whether this set contains another set.
>>> s1={1,2,3,4}
>>> s2={1,2,3,4,5,6,7}
>>> s1.issuperset(s2)
False
>>> s2.issuperset(s1)
Truepop
從集合中移除一個(gè)元素，如果集合為空，則報(bào)錯(cuò) Remove and return an arbitrary set element. Raises KeyError if the set is empty.
>>> s1={2,3,4,5}
>>> s1.pop()
2
>>> print(s1)
{3, 4, 5}
>>> s1.pop()
3
>>> s1.pop()
4
>>> s1.pop()
5
>>> s1.pop()
Traceback (most recent call last):
File "", line 1, in
KeyError: 'pop from an empty set' remove
移除集合中的一個(gè)元素，如果集合是空的，則報(bào)錯(cuò) Remove an element from a set; it must be a member. If the element is not a member, raise a KeyError.
>>> s1={1,2,3,4,5,6}
>>> s1.remove(4)
>>> print(s1)
{1, 2, 3, 5, 6}
>>> s1.remove(9)
Traceback (most recent call last):
File "", line 1, in
KeyError: 9 symmetric_difference
返回兩個(gè)集合的對(duì)稱差集的集合 Return the symmetric difference of two sets as a new set.
>>> s1={1,2,3,4}
>>> s2={6,7,8,9}
>>> s1.symmetric_difference(s2)
{1, 2, 3, 4, 6, 7, 8, 9}
>>> s3={1,2,3,4,5,6}
>>> s4={5,6,7,8,9,10}
>>> s3.symmetric_difference(s4)
{1, 2, 3, 4, 7, 8, 9, 10}symmetric_difference_update
與參數(shù)集合做對(duì)稱差集，并返回給自身 Update a set with the symmetric difference of itself and another.
>>> s1={1,2,3,4}
>>> s2={6,7,8,9}
>>> s2.symmetric_difference_update(s1)
>>> print(s2)
{1, 2, 3, 4, 6, 7, 8, 9}
>>> s3={1,2,3,4,5,6}
>>> s4={5,6,7,8,9,10}
>>> s3.symmetric_difference_update(s4)
>>> print(s3)
{1, 2, 3, 4, 7, 8, 9, 10}union
求兩個(gè)或多個(gè)集合的并集 Return the union of sets as a new set.
>>> s1={1,2,3,4,5,6}
>>> s2={5,6,7,8,9}
>>> s1.union(s2)
{1, 2, 3, 4, 5, 6, 7, 8, 9}
>>> s3={1,2,3,4}
>>> s4={6,7,8,9}
>>> s3.union(s4)
{1, 2, 3, 4, 6, 7, 8, 9}update
與另一個(gè)集合求并集，并返回給自身 Update a set with the union of itself and others.
>>> s3={1,2,3,4}
>>> s4={6,7,8,9}
>>> s3.update(s4)
>>> print(s3)
{1, 2, 3, 4, 6, 7, 8, 9} 當(dāng)前文章：創(chuàng)新互聯(lián)Python教程：Python之set集合的相關(guān)介紹
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