Re: Calculating a moving average
| От | Dann Corbit |
|---|---|
| Тема | Re: Calculating a moving average |
| Дата | |
| Msg-id | D425483C2C5C9F49B5B7A41F89441547055836@postal.corporate.connx.com обсуждение исходный текст |
| Ответ на | Calculating a moving average ("Vanole, Mike" <Mike.Vanole@cingular.com>) |
| Ответы |
Re: Calculating a moving average
|
| Список | pgsql-general |
Why not use a cursor?
P.S.
A moving average will look much better if you Hahn the tails.
To do a normal 7 point moving average, you take (x[i]+ x[i+1]+ x[i+2]+ x[i+3]+ x[i+4]+ x[i+5]+ x[i+6])/7 as point xprime[i] and (y[i]+ y[i+1]+ y[i+2]+ y[i+3]+ y[i+4]+ y[i+5]+ y[i+6])/7 as point yprime[i].
But when you start let x[0], y[0] be the first point, and then average the next 2 for the second point… until you get to 7 and then do the same thing in the other end. Otherwise, you get a very strange looking curve.
IMO-YMMV
From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Vanole, Mike
Sent: Wednesday, January 19, 2005 1:34 PM
To: pgsql-general@postgresql.org
Subject: [GENERAL] Calculating a moving average
Hi,
I need to calculate a moving average and I would like to do it with SQL, or a Pg function built for this purpose. I'm on Pg 7.4. Is this possible in Pg without a bunch of self joins, or is there a funtion available?
Thanks,
Mike
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