From: uncutstone wu <uncutstone@...>
Date: 2006-05-17T02:46:30+09:00
Subject: Re: In search of elegant indices searching


Nuralanur@aol.com 写道：

> Dear all,
>  
> I have a Hash, with equal-length Arrays as values, something like
>  
> my_hash={'x',[1,1,3,1,5,6],'w',[1,2,3,1,4,5],'y',[1,1,1,4,4,6],'z',[0,1,1,2,3,
> 4]}  .
>  
> Some of the values in the Arrays occur several times.
> Now, I am looking for an elegant way to extract, for  all the values
> of specified keys, all the indices
> where one or more variables do not change their values, i.e.,  something
> like
>  
> class Hash
>     def fixed_vars(which_vars)
>  
>          # some elegant code
>         return result
>     end
> end
>  
> res=my_hash.fixed_vars(['x','w'])
>  
> giving 
>  
> res={{'x'=>1,'w'=>1}=>[0,3],{'x'=>3,'w'=>3}=>[2],{'x'=>5,'w'=>4}=>[4],{'x'=>6,
> 'w'=>5}=>[5]}.
>  

Indeed, I really don't fully understand what you want , and the code 
below is hacked out and is definitively not elegant. But it works, and 
gives what you want .

module MyHash
  def fixed_vars(key1, key2)
    res = {}
    def res.[](key)
      self.each do |akey, aval|
        if akey == key
          return aval
        end
      end
      nil
    end
    a1 = self[key1]
    a2 = self[key2]
    len = a1.length
    recorded = []
    len.times do |i|
      if a1[i] == a2[i]
        h = {key1=>a1[i],key2=>a2[i]}
        res[h]=[] if res[h] == nil
        res[h] << i
        recorded << a1[i]
      end
    end
    len.times do |i|
      if a1[i] != a2[i] and
            (not recorded.include?(a1[i])) and
            (not recorded.include?(a2[i]))
        res[{key1=>a1[i],key2=>a2[i]}] = [] if 
res[{key1=>a1[i],key2=>a2[i]}] == nil
        res[{key1=>a1[i], key2=>a2[i]}] << i
      end
    end
    return res
  end
end

def testmy_hash
  my_hash={'x',[1,1,3,1,5,6],'w',[1,2,3,1,4,5],
         'y',[1,1,1,4,4,6],'z',[0,1,1,2,3,4]}
  my_hash.extend MyHash
  res = my_hash.fixed_vars('x','w')
  puts res.inspect
end

testmy_hash


Best regards.

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