[Python-ideas] exclusively1, common, exclusively2 = set1 - set2, set1 & set2, set2 - set1

[Paddy3118]

On Wednesday, 3 July 2013 21:50:35 UTC+1, Paddy3118 wrote:
>
> I found myself repeating something that I know I have used before, several 
> times: I get two sets of results, may be sets of the passing tests when a 
> design has changed, and I need to work out what has changed so work out 
>
> 1. What passed first time round
> 2. What passed both times.
> 3. What passed only the second time round.
>
> I usually use something like the set equations in the title to do this but 
> I recognise that this requires both sets to be traversed at least three 
> times which seems wasteful.
>
> I wondered if their was am algorithm to partition the two sets of data 
> into three as above, but cutting down on the number of set traversals?
>
> I also wondered that if such an algorithm existed, would it be useful 
> enough to be worth incorporating into the Python library? 
>
> Maybe defined as:
>
> exclusively1, common, exclusively2 = set1.partition(set2)
>

I've done a related blog entry Set divisions/partitions<http://paddy3118.blogspot.co.uk/2013/07/set-divisionspartitions.html> in 
which I try for a more general algorithm.



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