How to sum and group data by DATE in data frame
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 :) -- View this message in context: http://r.789695.n4.nabble.com/How-to-sum-and-group-data-by-DATE-in-data-frame-tp903708p4630119.html Sent from the R help mailing list archive at Nabble.com.
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