From: brabuhr@...
Date: 2009-06-09T05:42:17+09:00
Subject: Re: How to sort array ascending, except zero ?

On Mon, Jun 8, 2009 at 4:08 PM, Sebastian
Hungerecker<sepp2k@googlemail.com> wrote:
> Am Montag 08 Juni 2009 20:55:17 schrieb brabuhr@gmail.com:
>> Assuming a stable sorting algorithm
>
> Neither sort nor sort_by use a stable sorting algorithm though.

But, at least it was pretty fast even if it was not correct.  ;-)

require 'benchmark'
Infinity = 1.0/0.0
Benchmark.bm(25) do |b|
  a = (1..500000).map{|n| rand(10) - 20}
  b.report("A") {
    a.sort.sort_by{|n| n.zero? ? 1 : 0}
  }
  b.report("D") {
    tmp = a.partition{|x| x != 0 }
    tmp[0].sort + tmp[1]
  }
  b.report("F") {
    n = 0
    a.sort_by{|x| n+= 1; [x, n]}.sort_by{|n| n.zero? ? 1 : 0}
  }
  b.report("G") {
    tmp = a.sort.partition{|x| x != 0 }
    tmp[0] + tmp[1]
  }
  b.report("H") {
    tmp = a.sort.select{|x| x != 0 }
    tmp + ([0] * (a.size - tmp.size))
  }
end

ruby1.8 /tmp/z
                               user     system      total        real
A                          1.030000   0.160000   1.190000 (  1.313981)
D                          0.720000   0.170000   0.890000 (  0.996888)
F                         19.510000   1.270000  20.780000 ( 24.233460)
G                          0.800000   0.170000   0.970000 (  1.180949)
H                          0.540000   0.140000   0.680000 (  0.897509)

ruby1.9 /tmp/z
                               user     system      total        real
A                          0.440000   0.020000   0.460000 (  0.520912)
D                          0.250000   0.000000   0.250000 (  0.274845)
F                         17.720000   0.080000  17.800000 ( 19.969714)
G                          0.260000   0.000000   0.260000 (  0.299049)
H                          0.180000   0.000000   0.180000 (  0.210772)

jruby /tmp/z
                               user     system      total        real
A                          1.688000   0.000000   1.688000 (  1.641000)
D                          0.848000   0.000000   0.848000 (  0.849000)
F                         13.181000   0.000000  13.181000 ( 13.180000)
G                          0.678000   0.000000   0.678000 (  0.678000)
H                          0.591000   0.000000   0.591000 (  0.591000)