如何与s正确结合

2024-03-28 18:16:46 发布

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我知道任何带有空集合的python集合union都会产生它自己。但是当union在for循环中时,我检测到一些奇怪的行为。

看起来不错

num= set([2,3,4])
emp= set()
print num|emp
>>>set([2, 3, 4])

困惑

s = set()
inp = ["dr101-mr99","mr99-out00","dr101-out00","scout1-scout2","scout3-    scout1","scout1-scout4","scout4-sscout","sscout-super"]
for ele in inp:
  r = set(ele.split("-"))
  print r
  s.union(r)
print s
 >>>set(['mr99', 'dr101'])
    set(['out00', 'mr99'])
    set(['out00', 'dr101'])
    set(['scout1', 'scout2'])
    set(['scout1', 'scout3'])
    set(['scout4', 'scout1'])
    set(['scout4', 'sscout'])
    set(['super', 'sscout'])
    set([])

有人能告诉我为什么最后一组是空的吗? 输出应该是集合中的每个唯一元素吗?


Tags: fornumprintunioninpsetempscout2