Add isdisjoint
#34427
Add isdisjoint
#34427
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| function _isdisjoint(l, r) | ||
| hasfastin(r) && return !any(in(r), l) | ||
| hasfastin(l) && return !any(in(l), r) | ||
| haslength(r) && length(r) < FASTIN_SET_THRESHOLD && |
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Just a note, in issubset the conversion to Set can be done only if haslength(r), here you made the opposite choice... Was it for a specific reason? (I didn't think much about it, but indeed converting to Set when length is unknown seems like a better choice to me; what about updating issubset then?).
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Yes, converting to Set in general seemed like a good idea to me, with the exception of a fast path when the thing we're iterating over happens to be short.
base/abstractset.jl
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| return !any(in(r), l) | ||
| return !any(in(Set(r)), l) | ||
| end | ||
| if haslength(l) && haslength(r) && lenght(r) < length(l) |
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Sometimes lenght is not constant time (e.g. BitSet), and in some cases it might be computed twice here. Not a big deal at all (I don't have any example where this is an actual problem (this requires haslengh, !hasfastin and non-fast length)), but if this can be easily re-arranged to not compute the length twice, why not!
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I think we generally assume that length is constant time. Otherwise these checks are unlikely to be profitable. I don't think it's worth the extra complication. We're already doing a quadratic operation here.
test/sets.jl
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| for S in (Set, BitSet, Vector) | ||
| for (l,r) in ((S([1,2]), S([3,4])), | ||
| (S([5,6,7,8]), S([7,8,9])), | ||
| (S([1,2]), S([3,4])), | ||
| (S([5,6,7,8]), S([7,8,9])), | ||
| (S([1,2,3]), S()), | ||
| (Set(), Set()), |
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Should be S(). Or does it not work properly with BitSet and Vector?
This was added in #13192, but the PR became stale. We've also changed a bit how we write these kinds of algorithms, so make use of the tools we have (e.g. `fastin`).
rfourquet
added
the
collections
* add isdisjoint (JuliaLang/julia#34427) * fix formatting * Use correct version in README entry * Add missing link to README And sort/unify the entries using NEWS-update.jl Co-authored-by: colinxs <me@colinxsummers.com> Co-authored-by: Martin Holters <martin.holters@hsu-hh.de>
This was added in #13192, but the PR became stale. We've also changed
a bit how we write these kinds of algorithms, so make use of the tools
we have (e.g.
fastin).