From: Gabor Grothendieck <ggrothendieck_at_gmail.com>

Date: Wed 14 Dec 2005 - 00:08:40 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Dec 14 01:05:11 2005

Date: Wed 14 Dec 2005 - 00:08:40 EST

Your variable mat is not a matrix; its a data frame. Check it with:

class(mat)

Here is an example:

x <- cbind(A = 1:4, B = 5:8)

tt <- c(1, 3:4, 6)

library(zoo)

x.zoo <- zoo(x, tt)

x.ts <- as.ts(x.zoo)

On 12/13/05, Alvaro Saurin <saurin@dcs.gla.ac.uk> wrote:

*>
**> Hi,
**>
*

> First, thank you. It 'almost' works: I can convert a matrix to a

*> 'zoo' object, but it can not convert it to a 'ts'.
**>
**> The sitruation is this: I load a set of samples with
**>
**> > h_types <- list (0, 0, character(0), character(0), 0, 0, 0, 0, 0)
**> > h_names <- list ("time", "flow", "type", "dir", "seq", "ts", "x",
**> "rtt", "size")
**> > pcks_file <- pipe ("grep ' P ' server.dat"), "r")
**> > pcks <- scan (pcks_file, what = h_types, comment.char = '#',
**> fill = TRUE)
**> Read 1429 records
**>
**> > mat <- data.frame (pcks)
**> > colnames (mat) <- h_names
**> > mat
**>
**> time flow type dir seq ts x rtt size
**> 1 1.000893 0 P + 0 1.000893 1472 0.000000 1472
**> 2 1.514454 0 P + 1 1.514454 2944 0.513142 1472
**> 3 2.015093 0 P + 2 2.015093 2944 0.513142 1472
**> 4 2.515025 0 P + 3 2.515025 4806 0.504488 1472
**> 5 2.821976 0 P + 4 2.821976 5730 0.496728 1472
**> 6 3.078931 0 P + 5 3.078931 5832 0.489744 1472
**> 7 3.331897 0 P + 6 3.331897 5832 0.489744 1472
**>
**> [...]
**>
**> 1425 176.925504 0 P + 1424 176.925504 12141 0.764699 1472
**> 1426 177.039489 0 P + 1425 177.039489 12141 0.764699 1472
**> 1427 177.153469 0 P + 1426 177.153469 12141 0.764699 1472
**> 1428 177.267464 0 P + 1427 177.267464 12141 0.764699 1472
**> 1429 177.381434 0 P + 1428 177.381434 12141 0.764699 1472
**>
**> Then I convert it to a 'zoo', removing the 'time' column from the input
**>
**> > last_col <- ncol (mat)
**> > range_cols <- 2:last_col
**> > matrix_values <- mat [,range_cols]
**> > z <- zoo (matrix_values, mat $ time)
**>
**> So far, everything is fine. But then I need to apply a function to
**> samples taken every t seconds, ie, the mean every 10 seconds. And,
**> AFAIK, rapply needs a constant 'width', something that can only be
**> obtained with regular time series... But if I try to get a 'ts'
**> object from my 'zoo' I get
**>
**> > as.ts (z)
**> Error in if (del == 0 && to == 0) return(to) :
**> missing value where TRUE/FALSE needed
**>
**> Ummm, do you know if there is any error in my 'zoo' object? Has it
**> the right format? Or, could I avoid the conversion and use the
**> 'rapply' function but on time intervals (instead of points intervals)?
**>
**> Thank you very much.
**>
**> Alvaro
**>
**>
**> On 12 Dec 2005, at 16:31, Gabor Grothendieck wrote:
**>
**> > First we generate some sample data x and its times tt.
**> > Then using the zoo package we create an irregularly
**> > spaced time series. Now if you want a regularly spaced
**> > time series convert it to ts class. After loading zoo as
**> > shown below, the R command vignette("zoo") gives more info.
**> >
**> > x <- 1:4
**> > tt <- c(1, 3, 4, 6)
**> >
**> > library(zoo)
**> > x.zoo <- zoo(x, tt) # irregularly spaced time series
**> > x.ts <- as.ts(x.zoo) # regular time series with NAs
**> >
**> >
**> > On 12/12/05, Alvaro Saurin <saurin@dcs.gla.ac.uk> wrote:
**> >>
**> >> Hi,
**> >>
**> >> I am a R begginer and I have a small problem with time series. I was
**> >> wondering if someone could help me
**> >>
**> >> I am collecting data from packets going through a network, and using
**> >> R for obtaining some simple statistics of connections. However, my
**> >> data is not collected at a constant frequency, so I would like to
**> >> create a evenly spaced TS from my traces, using the minimum time
**> >> difference between two samples as the period for my new TS, and
**> >> filling the gaps with NA (or 0s).
**> >>
**> >> I think ther must be some simple solution for this... Anyone could
**> >> help me?
**> >>
**> >> Thanks in advance.
**> >>
**> >> --
**> >> Alvaro Saurin <alvaro.saurin@gmail.com> <saurin@dcs.gla.ac.uk>
**> >>
**> >> ______________________________________________
**> >> R-help@stat.math.ethz.ch mailing list
**> >> https://stat.ethz.ch/mailman/listinfo/r-help
**> >> PLEASE do read the posting guide! http://www.R-project.org/posting-
**> >> guide.html
**> >>
**>
**> --
**> Alvaro Saurin <alvaro.saurin@gmail.com> <saurin@dcs.gla.ac.uk>
**>
**>
**>
**>
*

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Dec 14 01:05:11 2005

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