Hi Jim, Oh wow thanks so much. One question though, did you notice that the 12:00:00 slot is missing entirely from the output? It shows 11:52:30 and 12:07:30, but not 12:00:00. Actually after another review I see that it's missing the 12, 12:15, and 12:30?
>2012-07-22 11:52:30 2012-07-22 12:07:30 2012-07-22 12:22:30 2012-07-22 12:37:30 > NA 22.33333 NA 24.00000 >2012-07-22 12:52:30 > 20.00000 Any ideas how to fix this? Thanks again! Jason On Mon, Aug 27, 2012 at 1:40 PM, jim holtman <jholt...@gmail.com> wrote: > try this: > > > > x <- read.table(text = "2012-07-22 12:12:00, 21 > + 2012-07-22 12:15:00, 22 > + 2012-07-22 12:18:00, 24 > + 2012-07-22 12:39:00, 21 > + 2012-07-22 12:45:00, 25 > + 2012-07-22 12:49:00, 26 > + 2012-07-22 12:53:00, 20 > + 2012-07-22 13:00:00, 18 > + 2012-07-22 13:06:00, 22", colClasses = c("POSIXct", "integer"), sep = > ',') > > # get minimum at an hour granularity > > tMin <- trunc(min(x$V1), units = 'hour') > > # back off 7.5 minute > > tMin <- tMin - (7.5 * 60) > > # create sequence for 'cut' > > cSeq <- seq(tMin, max(x$V1) + (7.5 * 60), by = '15 min') > > # now split and average > > cCut <- cut(x$V1, cSeq) > > # compute means > > tapply(x$V2, cCut, mean) > 2012-07-22 11:52:30 2012-07-22 12:07:30 2012-07-22 12:22:30 2012-07-22 > 12:37:30 > NA 22.33333 NA > 24.00000 > 2012-07-22 12:52:30 > 20.00000 > > > > > On Mon, Aug 27, 2012 at 9:53 AM, Jason Gilmore <w...@wjgilmore.com> wrote: > > > > Hi, > > > > I'm pretty new to R and have run into a task which although I'm certain > is > > within R's capabilities, falls outside of mine. :-) Consider the > following > > data set: > > > > 2012-07-22 12:12:00, 21 > > 2012-07-22 12:15:00, 22 > > 2012-07-22 12:18:00, 24 > > 2012-07-22 12:39:00, 21 > > 2012-07-22 12:45:00, 25 > > 2012-07-22 12:49:00, 26 > > 2012-07-22 12:53:00, 20 > > 2012-07-22 13:00:00, 18 > > 2012-07-22 13:06:00, 22 > > > > My task involves creating a data set which *averages* these values at a > > resolution of 15 minutes, meaning that I need to average the values > falling > > within 7.5 minutes of a 15 minute increment. Therefore given the above > data > > set I need to treat it as three groups: > > > > 2012-07-22 12:12:00, 21 > > 2012-07-22 12:15:00, 22 > > 2012-07-22 12:18:00, 24 > > > > 2012-07-22 12:39:00, 21 > > 2012-07-22 12:45:00, 25 > > 2012-07-22 12:49:00, 26 > > > > 2012-07-22 12:53:00, 20 > > 2012-07-22 13:00:00, 18 > > 2012-07-22 13:06:00, 22 > > > > The end result should look like this: > > > > 2012-07-22 12:15:00, 22.33 > > 2012-07-22 12:30:00, NA <- Because this 15 minute slot did not previously > > exist > > 2012-07-22 12:45:00, 24 > > 2012-07-22 1:00:00, 20 > > > > Any help much appreciated. I've been working on this for several hours > with > > little success. I'm able to identify the missing (NA) value using zoo/xts > > but can't seem to sort out the averaging matter. > > > > Thanks so much! > > Jason > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > > > > -- > Jim Holtman > Data Munger Guru > > What is the problem that you are trying to solve? > Tell me what you want to do, not how you want to do it. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.