From: Regis d'Aubarede <lists@...>
Date: 2012-11-30T00:42:12+09:00
Subject: Re: Getting the smallest Items of an Array

> def n_min(l,n) (1..n).map {a=l.min ; l=l-[a]; a } end
>
>           array.sort[0, n]
>           n_min array, n


You compar ruby implementation for n_min() with c implementation for 
sort...

here result with a qsort from http://rosettacode.org, REP=10

class Array
  def qsort
    return self if length <= 1
    pivot = self[0]
    less, greatereq = self[1..-1].partition { |x| x < pivot }
    less.qsort +
      [pivot] +
      greatereq.qsort
  end
end


Generating data...
done
                                    user     system      total 
real

4/1024 items sort              0.031000   0.000000   0.031000 ( 
0.029001)
4/1024 items n_min              0.000000   0.000000   0.000000 ( 
0.006001)

4/131072 items sort            6.022000   0.016000   6.038000 ( 
6.039345)
4/131072 items n_min            0.671000   0.016000   0.687000 ( 
0.701040)

20/1024 items sort             0.031000   0.000000   0.031000 ( 
0.028002)
20/1024 items n_min             0.031000   0.000000   0.031000 ( 
0.027001)

20/131072 items sort           6.069000   0.031000   6.100000 ( 
6.117349)
20/131072 items n_min           3.510000   0.078000   3.588000 ( 
3.595206)

100/1024 items sort            0.031000   0.000000   0.031000 ( 
0.030002)
100/1024 items n_min            0.125000   0.000000   0.125000 ( 
0.135008)

100/131072 items sort          6.286000   0.000000   6.286000 ( 
6.300360)
100/131072 items n_min         17.223000   0.265000  17.488000 ( 
17.496001)

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