Detailed explanation of set syntax in python3-Python Tutorial-php.cn

Detailed explanation of set syntax in python3

Y2J

Release： 2017-05-03 15:45:35

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This article mainly summarizes the relevant information about the syntax of set (set) in python3. The article gives detailed sample code, which has certain reference value for everyone. Friends who need it can take a look below.

Introduction

set Gu Mingsiyi is a set, and the elements of the set are unique and unordered. Putting some elements in a { } forms a set. The set can be of multiple data types (but not lists, sets, dictionaries, but can be tuples)

A set is an unordered non-repeating element of sets. Basic functionality includes relationship testing and elimination of duplicate elements. Set objects also support mathematical operations such as union, intersection, difference and sysmmetric difference.

Braces or the set() function can be used to create a set. Note: To create an empty collection, you must use set() instead of {}. {} is used to create an empty dictionary;

The specific syntax is summarized as follows.

add (add elements)

name = set([&#39;Tom&#39;,&#39;Lucy&#39;,&#39;Ben&#39;])
name.add(&#39;Juny&#39;)
print(name)

#输出：{&#39;Lucy&#39;, &#39;Juny&#39;, &#39;Ben&#39;, &#39;Tom&#39;}

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clear (clear all elements)

name = set([&#39;Tom&#39;,&#39;Lucy&#39;,&#39;Ben&#39;])
name.clear()
print(name)

#输出：set()

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copy (copy set collection)

name = set([&#39;Tom&#39;,&#39;Lucy&#39;,&#39;Ben&#39;])
new_name = name.copy()
print(new_name)

#输出：{&#39;Tom&#39;, &#39;Lucy&#39;, &#39;Ben&#39;}

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difference (return Different elements in two or more sets and generate a new set)

A = set([2,3,4,5])
B = set([3,4])
C = set([2])
n = n1.difference(n2,n3)
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

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difference_update (Delete the elements in set A that exist in set B.)

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

#输出：{2, 3}

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discard (move Remove elements)

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

#输出：{2, 4}

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intersection(Get the intersection and generate a new set)

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

#输出：{4, 5}

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intersection_update(Get the intersection and modify the original set)

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

#输出：{4, 5}

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isdisjoint(Judge the intersection, Returns False if yes, True if not)

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

#输出：False

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issubset(Judge subset)

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

#输出：True
#A是B的子集

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issuperset(Judge parent set)

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

# 输出：True
#B是A的父集

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pop(Randomly remove an element)

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

# 输出：{3, 4, 5} 2

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remove(remove the specified element)

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

# 输出：{3, 4, 5}

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symmetric_difference(take the intersection and generate a new set)

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

# 输出：{2, 3, 6, 7}

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symmetric_difference_update(take the intersection and change the original set)

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}

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union (take the union and generate a new set)

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

# 输出：{2, 3, 4, 5, 6, 7}

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update (take the union and change the original set)

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}

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