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harms/unshared.ijs

Created May 21, 2012 13:40
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Example J solution to (Ruby) question asked by Bill Tozier
Raw
unshared.ijs
unshared=: (-. , -.~) &. setForm
setForm=: convert :. revert
convert=: [: ; (<@(j. i.@#))/.~
revert=: /:~ @ {. @ |: @: +.
A=. 1 2 2 3 3 4 5
B=. 2 3 3 3 3 4 5 6
A unshared B
1 2 3 3 6
NB. Main concept is prominent: each set less the other, unioned. (-. , -.~)
NB. Inspired by https://twitter.com/#!/Vaguery/status/204003580422782976
NB. The version presented above was refactored from the following code, which was originally published in this gist. This is an example of how refactoring often occurs by algebraic reduction.
setForm=: convert :. revert
convert=: (<@(j. i.@#))/.~
revert=: (/:~) @ {. @ |: @: +.
DyadicSets=: 1 :' ;@>@{. u ;@}. '
unshared=: ((-. , -.~)DyadicSets @: ;) &. setForm
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