Re: graphing time series data

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От Louis-David Mitterrand
Тема Re: graphing time series data
Дата
Msg-id 20100414161152.GA17805@apartia.fr
обсуждение исходный текст
Ответ на Re: graphing time series data  (Pavel Stehule <pavel.stehule@gmail.com>)
Ответы Re: graphing time series data  (Pavel Stehule <pavel.stehule@gmail.com>)
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On Wed, Apr 14, 2010 at 06:06:59PM +0200, Pavel Stehule wrote:
> I don't understand well. Why you don't use a function date_trunc(),
> 
> select date_trunc('week', created), count(*)
> from price
> group by date_trunc('week', created)

Because if a price doesn't change for more than a week, then some weeks
will have bad statistical distribution (i.e not including prices which
only have their 'modified' updated). So I (think I) need to (1) generate
the weeks separately and (2) average prices that are current for each
week.

But I could be missing something obvious.



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