From: Gabor Grothendieck <ggrothendieck_at_gmail.com>

Date: Thu, 07 Apr 2011 15:41:30 -0400

5 5 19.0

6 7 19.8

Date: Thu, 07 Apr 2011 15:41:30 -0400

On Thu, Apr 7, 2011 at 2:29 PM, Rita Carreira <ritacarreira_at_hotmail.com> wrote:

*>
*

> Hello everyone!

*> I have a data frame of 136 variables with 270 observations. I would like to create a new data frame such that each element of that data frame contains the maximum value of the 6 prior lags of the initial data frame. So for example, if my original data frame, A, were
**> A1=c(7.72, 7.94, 7.56, 7.54, 0.93, 0.59, 7.21, 8.00, 7.19, 7.57)A2=c(4.27, 3.70, 3.80, 3.67, 3.83, 3.95, 4.02, 2.06, 3.28, 2.17)A3=c(4.16, 2.91, 3.89, 3.73, 4.00, 3.81, 3.86, 1.88, 3.74, 3.75)A4=c(3.56, 3.27, 3.42, 3.32, 3.48, 3.54, 3.60, 2.04, 3.38, 3.37)A5=c(8.24, 8.67, 8.49, 0.00, 9.39, 0.00, 8.49, 8.94, 0.00, 0.00)A6=c(4.28, 4.18, 4.20, 4.14, 4.40, 4.20, 4.20, 4.15, 4.17, 4.16)
**> A <- cbind(A1, A2, A3, A4, A5, A6)
**> My new data frame, Amax, where each element is amax(i,j)=max[a(i-1,j), a(i-2,j), a(i-3,j), a(i-4,j), a(1-5,j), a(i-6,j)] would be:NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 7.94
**> 4.27
**> 4.16
**> 3.56
**> 9.39
**> 4.40 7.94
**> 4.02
**> 4.00
**> 3.60
**> 9.39
**> 4.40 8.00
**> 4.02
**> 4.00
**> 3.60
**> 9.39
**> 4.40 8.00
**> 4.02
**> 4.00
**> 3.60
**> 9.39
**> 4.40 8.00
**> 4.02
**> 4.00
**> 3.60
**> 9.39
**> 4.40
**> So the question is: what is the most efficient way of doing this in R?
**> Thanks!Rita ________________________________________ "If you think education is expensive, try ignorance"--Derek Bok
*

See rollmax in the zoo package and see ?rollmax for the various options. e.g. using the built in BOD data frame:

*> library(zoo)
**> as.data.frame(rollmax(BOD, 3, na.pad = TRUE, align = "right"))
*

Time demand

1 NA NA 2 NA NA 3 3 19.0 4 4 19.0

5 5 19.0

6 7 19.8

-- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-help_at_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.Received on Thu 07 Apr 2011 - 19:43:55 GMT

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