Python 设计模式 - 集合

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  简述

  集合可以定义为可迭代、可变且不包含重复元素的无序集合。在 Python 中，集合类是数学集合的一种表示法。使用集合的主要优点是它包含用于检查特定元素的高度优化的方法。

  Python 包含一个单独的类别，称为冻结集。这些集合是不可变对象，仅支持产生所需结果的方法和运算符。
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  如何实现集合？

  以下程序有助于实施集合 -

  
  # Set in Python
  # Creating two sets
  set1 = set()
  set2 = set()
  # Adding elements to set1
  for i in range(1, 6):
     set1.add(i)
  # Adding elements to set2
  for i in range(3, 8):
     set2.add(i)
  print("Set1 = ", set1)
  print("Set2 = ", set2)
  print("\n")
  # Union of set1 and set2
  set3 = set1 | set2# set1.union(set2)
  print("Union of Set1 & Set2: Set3 = ", set3)
  # Intersection of set1 and set2
  set4 = set1 & set2# set1.intersection(set2)
  print("Intersection of Set1 & Set2: Set4 = ", set4)
  print("\n")
  # Checking relation between set3 and set4
  if set3 > set4: # set3.issuperset(set4)
     print("Set3 is superset of Set4")
  elif set3 < set4: # set3.issubset(set4)
     print("Set3 is subset of Set4")
  else : # set3 == set4
     print("Set3 is same as Set4")
  # displaying relation between set4 and set3
  if set4 < set3: # set4.issubset(set3)
     print("Set4 is subset of Set3")
     print("\n")
  # difference between set3 and set4
  set5 = set3 - set4
  print("Elements in Set3 and not in Set4: Set5 = ", set5)
  print("\n")
  # checkv if set4 and set5 are disjoint sets
  if set4.isdisjoint(set5):
     print("Set4 and Set5 have nothing in common\n")
  # Removing all the values of set5
  set5.clear()
  print("After applying clear on sets Set5: ")
  print("Set5 = ", set5)
  

  输出

  上述程序生成以下输出 -

  

  可以使用以下程序演示冻结集 -

  
  normal_set = set(["a", "b","c"])
  # Adding an element to normal set is fine
  normal_set.add("d")
  print("Normal Set")
  print(normal_set)
  # A frozen set
  frozen_set = frozenset(["e", "f", "g"])
  print("Frozen Set")
  print(frozen_set)
  

  输出

  上述程序生成以下输出 -