[R] How to sum and group data by DATE in data frame

[R. Michael Weylandt]

Can you provide a reproducible example? use dput() to send your data
in a reproducible and user-friendly format. (It might not look user
friendly, but trust me, it is) If x is really long, perhaps just
dput(head(x, 25)) will suffice.

Just a guess as to your problem: I'm not familiar with the
timeSequence function -- what package is it from? My guess is that the
days it's producing are not properly aligned with the days of your
time series object. Can you try it with something closer to my
example?

Best,
Michael

On Tue, May 15, 2012 at 12:42 PM, Cren <oscar.soppelsa at bancaakros.it> wrote:
> Thank you for your help, Michael.
>
> I used *aggregate(x, by = timeSequence(by = "day"), FUN = sum)* but the
> results is very different from *sum(x[1:13])*, where 13 is the number of
> daily observations I've sampled.
>
> Michael Weylandt wrote
>>
>> How are you using aggregate()? It seems to sum for me...
>>
>> z <- zoo(1:50, seq.POSIXt(from = Sys.time(), by = "30 min", length.out =
>> 50))
>>
>> aggregate(z, as.Date(time(z)), sum)
>>
>> Best,
>> Michael
>>
>> On Tue, May 15, 2012 at 11:52 AM, Cren <oscar.soppelsa@> wrote:
>>> Hello,
>>>
>>> I have a time series with intraday datas, sampled every 30'; I would need
>>> to
>>> aggregate them in this way: summing up all datas within a day.
>>>
>>> I tried to use *aggregate(...)* function to get my goal, but it
>>> aggregates
>>> in wrong way (I did not understand how so far); what I need is like
>>> *sum(...)* function applied to datas within the same day.
>>>
>>> Thank you :)
>>>
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>>
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>
>
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> Sent from the R help mailing list archive at Nabble.com.
>
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