From: Lyndon Samson <lyndon.samson@...>
Date: 2005-10-18T08:16:10+09:00
Subject: Re: How to get non-unique elements from an array?

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 user system total real
index 1.344000 0.000000 1.344000 ( 1.437000)
grep 3.875000 0.000000 3.875000 ( 4.266000)
scan 2.703000 0.000000 2.703000 ( 3.188000)
inject 1.625000 0.000000 1.625000 ( 1.812000)
gsub 3.078000 0.000000 3.078000 ( 3.547000)
bits 0.969000 0.000000 0.969000 ( 1.062000)
include 1.250000 0.000000 1.250000 ( 1.469000)

BMN =3D 50000
bm(5) do |bx|
bx.report('index ') { BMN.times { a.select{|e| a.index(e) !=3Da.rindex(e)}.=
uniq
} }
bx.report('grep ') { BMN.times { a.select{|e| a.grep(e).length > 1}.uniq } =
}
bx.report('scan ') { BMN.times {
a.sort.join('').to_s.scan(/(\d+)\s(\1)+/).flatten.uniq
} }
bx.report('inject') { BMN.times { a.uniq.inject(a.dup) { |b,i|b.delete_at(
b.index(i)) ; b } } }
bx.report('gsub ') { BMN.times
{a.to_s.gsub(/(.)(?!.*\1)/,'').split('').map{|i|i.to_i}
} }
bx.report('bits ') { BMN.times {
bn =3D bn2 =3D 0
a.each {|el|(bn2 |=3D (1<<el) if bn[el] =3D=3D 1) | bn |=3D (1<<el) }
#0.upto(a.length) { |bitNdx| puts bitNdx if bn2[bitNdx] =3D=3D 1 }
} }
bx.report('include') { BMN.times { t=3D[]; a.select{ |e| r=3Dt.include?e; t=
<<e;r
}.uniq } }

end

Nyah nyah, unlimited length bitstrings win :-) No output array of course bu=
t
the results are encoded in Fixnum/Bignum bits.

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