Python集合操作奇怪的行为

Question

我有下面的代码片段

seta = ["apple","orange","grapes","mango", "starfruit"]
setb = ["papaya","mango","jackfruit","grapes","lychee"]

def setOperation(seta, setb):
    union = set(seta) | set(setb)
    print(list(union)) 
    intersection = set(seta) & set(setb)
    print(list(intersection))
    difference = set(seta) - set(setb)
    print(list(difference))
    difference = set(setb) - set(seta)
    print(list(difference))
    sdifference = set(seta) ^ set(setb)
    print(list(sdifference))
    print(list(frozenset(set(seta))))
    
setOperation(seta,setb)

每次我运行它时，它都会产生不同的输出。就像-

['jackfruit', 'apple', 'mango', 'starfruit', 'grapes', 'lychee', 'orange', 'papaya']                                          
['grapes', 'mango']                                                                                                           
['orange', 'apple', 'starfruit']                                                                                              
['jackfruit', 'papaya', 'lychee']                                                                                             
['jackfruit', 'apple', 'starfruit', 'lychee', 'papaya', 'orange']                                                             
['orange', 'apple', 'grapes', 'mango', 'starfruit']

和

['grapes', 'mango', 'apple', 'orange', 'starfruit', 'lychee', 'papaya', 'jackfruit']                                          
['grapes', 'mango']                                                                                                           
['starfruit', 'apple', 'orange']                                                                                              
['lychee', 'papaya', 'jackfruit']                                                                                             
['apple', 'orange', 'starfruit', 'lychee', 'papaya', 'jackfruit']                                                             
['grapes', 'starfruit', 'mango', 'apple', 'orange']

但我希望输出如下所示-

['apple', 'grapes', 'jackfruit', 'lychee', 'mango', 'orange', 'papaya', 'starfruit']
['grapes', 'mango']
['apple', 'orange', 'starfruit']
['jackfruit', 'lychee', 'papaya']
['apple', 'jackfruit', 'lychee', 'orange', 'papaya', 'starfruit']

由于这个顺序的改变，我再次没有通过一次代码竞赛考试。如果我错过了一些简单的事情或做了什么愚蠢的事情，请一定要让我知道。我希望输出按字典序排列。提亚

Answer 1

集合是无序的，所以你不能期望得到一致的顺序。因为您的预期输出是按排序顺序的，所以您可以简单地查看排序后的并集/交集等，如下所示：

seta = set(["apple","orange","grapes","mango", "starfruit"])
setb = set(["papaya","mango","jackfruit","grapes","lychee"])

print(sorted(seta | setb)) # Union
print(sorted(seta & setb)) # Intersection
# ... etc ...

Answer 2

Set是Python中的无序数据结构。假设您希望输出按字典顺序排列，只需在print命令中添加'sorted()‘即可：

seta = ["apple","orange","grapes","mango", "starfruit"]
setb = ["papaya","mango","jackfruit","grapes","lychee"]

def setOperation(seta, setb):
    union = set(seta) | set(setb)
    print(sorted(union)) 
    intersection = set(seta) & set(setb)
    print(sorted(intersection))
    difference = set(seta) - set(setb)
    print(sorted(difference))
    difference = set(setb) - set(seta)
    print(sorted(difference))
    sdifference = set(seta) ^ set(setb)
    print(sorted(sdifference))
    print(sorted(frozenset(set(seta))))
    
setOperation(seta,setb)

输出：

['apple', 'grapes', 'jackfruit', 'lychee', 'mango', 'orange', 'papaya', 'starfruit']
['grapes', 'mango']
['apple', 'orange', 'starfruit']
['jackfruit', 'lychee', 'papaya']
['apple', 'jackfruit', 'lychee', 'orange', 'papaya', 'starfruit']
['apple', 'grapes', 'mango', 'orange', 'starfruit']