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From Mano <manoka...@gmail.com>
Subject Re: ranking a big list
Date Sat, 06 Feb 2010 16:53:06 GMT
On Sat, Feb 6, 2010 at 9:17 PM, Mano <manokaran@gmail.com> wrote:

>
> On Sat, Feb 6, 2010 at 6:57 PM, Metin Akat <akat.metin@gmail.com> wrote:
>
>> Hi,
>> What if 2 students have score of 200 and the next 3 have score of 199?
>> How do you decide who is fourth?
>>
>>
> There is no fourth rank in that case. Only first (the 2 200's) third (the 3
> 199's) and sixth etc ranks.
>

To elaborate, the rank here is to help infer how many students have scored
better than a given score. Thought of the following scheme. Any pitfalls in
this?

map: function(doc){
    emit(doc.score, 1);
}
reduce: function(keys, values){
    return sum(values);
}

So, to get the rank of, say, 186, I'll query the view with the key: 187 in
descending order. Will update after I try this out.

thanks,
mano

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