Re: Algorithm for randomly choosing a question

Udi Oron <[email protected]> Sun, 8 Jul 2012 12:25:21 +0300
Newsgroups	gmane.culture.hackers.israel
Message-ID	<CAAhvjANZVpeWLvA34rK6hNSaJApNz9zZPfvG=p-VGb8cRVtHMQ@mail.gmail.com>
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Hi!

On Sat, Jul 7, 2012 at 7:53 AM, Omer Zak <w1-W6cp89mEpD1mR6Xm/[email protected]> wrote:

> I want the application to be able to select any question randomly, but
> with different weights, so that:
> - A question the user never saw has weight of (say) 0.5.
> - A question the user answered wrongly has weight of 1 (i.e. such a
> question is twice more likely to be presented than a question never
> seen).
> - A question the user answered correctly has weight of 0.005 (i.e. it is
> 100 times less likely to be seen again than a question never seen
> before).



Keep three lists with pointers to "unasked" "wrong" and "correct"
questions, moving questions between them.
First choose from which list to pick your question (abuse length of list *
weight for each list.)
Than pick up a random question from your chosen list.
if RAM is a problem, keep the lists offline :-)

Udi.

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      <p><div dir="ltr"><div>Hi!</div><div><br></div><div>On Sat, Jul 7, 2012 at 7:53 AM, Omer Zak &lt;<a href="mailto:w1-W6cp89mEpD1mR6Xm/[email protected]">w1-W6cp89mEpD1mR6Xm/[email protected]</a>&gt; wrote:</div><blockquote class="gmail_quote" style="border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;">

I want the application to be able to select any question randomly, but<br>with different weights, so that:<br>- A question the user never saw has weight of (say) 0.5.<br>- A question the user answered wrongly has weight of 1 (i.e. such a<br>

question is twice more likely to be presented than a question never<br>seen).<br>- A question the user answered correctly has weight of 0.005 (i.e. it is<br>100 times less likely to be seen again than a question never seen<br>

before).</blockquote><div><br></div><div><br></div><div>Keep three lists with pointers to &quot;unasked&quot; &quot;wrong&quot; and &quot;correct&quot; questions, moving questions between them.</div><div>First choose from which list to pick your question (abuse length of list * weight for each list.)</div>

<div>Than pick up a random question from your chosen list.</div><div>if RAM is a problem, keep the lists offline :-)</div><div><br></div><div>Udi.</div></div>
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