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From Robert Newson <robert.new...@gmail.com>
Subject Re: how to sum values of a view in a date range?
Date Thu, 09 Jun 2011 17:12:50 GMT
Average isn't going to be possible without introducing compound
rounding errors (which, in my opinion, render the results useless).

The suggestion to use _stats sounded right to me. That will give you
both the count of items and the sum of those items, perform the final
(single) division in the client to avoid compound rounding errors.

B.

On 9 June 2011 18:04, Sean Copenhaver <sean.copenhaver@gmail.com> wrote:
> Yowza, I missed a lot in this thread. Yeah I thought you needed sum, but I
> provided a lot of examples of querying with some test data on your
> stackoverflow question. I hope that helps. It would actually be nice to see
> a built in _avg reduce function though.
>
>
> On Thu, Jun 9, 2011 at 12:39 PM, Robert Newson <robert.newson@gmail.com>wrote:
>
>> One minor point, your documents won't sort correctly (and therefore
>> your sums will be wrong). A string of this form "[2011, 6, 7, 10, 55]"
>> will not sort the same as the array you intended [2011, 6, 7, 10, 55].
>>
>> B.
>>
>> On 9 June 2011 17:36, Fabio Di Bernardini <fdb@altraqua.com> wrote:
>> > I need to make a chart with hourly sum of values restricted to March. So
>> I
>> > don't need one number with the sum of whole March month.
>> >
>> >
>> > 2011/6/9 David Hardtke <david@cloudant.com>
>> >
>> >> Hi Fabio,
>> >>
>> >> This should work.  You can use the _sum builtin as reduce:
>> >>
>> >> "reduce":"_sum"
>> >>
>> >> You then need to query your view with the proper group level and a
>> startkey
>> >> and endkey:
>> >>
>> >> GET
>> >>
>> db/_design/power/_view/watt?group_level=2&startkey=[2011,3]&endkey=[2011,4]&inclusive_end=false
>> >>
>> >> That gives you the sum for the month of March.
>> >>
>> >>
>> >>
>> >>
>> >> On 06/09/11 09:06, Fabio Di Bernardini wrote:
>> >>
>> >>> Il 09/06/2011 17:18, Fabio Di Bernardini ha scritto:
>> >>>
>> >>>> If I have a map function emitting a timestamp as key ad a number
as
>> >>>> document, how to get sum of values selecting a date range?
>> >>>>
>> >>>
>> >>> More datails here:
>> >>>
>> >>>
>> http://stackoverflow.com/questions/6294794/how-to-sum-values-of-a-view-in-a-date-range-using-couchdb
>> >>>
>> >>
>> >>
>> >
>>
>
>
>
> --
> “The limits of language are the limits of one's world. “ -Ludwig von
> Wittgenstein
>

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