> -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Jon Toledo > Sent: Monday, September 03, 2012 10:59 PM > To: r-help@r-project.org > Subject: [R] Create a function to number each repeated visit or > measurements > > > Hi dear R list members, > I am trying to create a numerical variable that tracks the > visits/entries that a subject has had. For example having a database of > repeated serial measurements that are ordered by subject and time. So I > would get a variable that says 0 for baseline visit/measurement, 1 for > the second etc. > In my case the unique identifier for each subject is AreaID > Will the following code I can number the visits as long as I create as > many lines as visits. > But there is probably a way of coding a function or maybe there is > already a function. > DUP<-rep(0,length(AreaID))DUP[2:length(DUP)]<- > sapply(2:(length(AreaID),function(x) ifelse(AreaID[x]==AreaID[x- > 1],1,DUP[x]))DUP[3:length(DUP)]<-sapply(3:( > length(AreaID),function(x) ifelse(AreaID[x]==AreaID[x-2],2,DUP[x])) > My Guess was: > AddLag<-function(x) { DUP<-c(rep(0,length(x))) for (i in > 1:(max(as.numeric(GraphArtDB$Measure))+2)){ > DUP[(i+1):length(x)]<-sapply(((i+1):length(x)),function(x) > ifelse(x[i]==x[x-i],i,DUP[x])) } return(DUP) > } > > But it didn´t work. > Any suggestions? > > Thanks in advance >
Your email was scrambled and therefore difficult to decipher. However, using the plyr package, you could do something like library(plyr) ddply(your_data_frame,"AreaID",transform,visit=0:(length(AreaID)-1)) Hope this is helpful, Dan Daniel J. Nordlund Washington State Department of Social and Health Services Planning, Performance, and Accountability Research and Data Analysis Division Olympia, WA 98504-5204 ______________________________________________ 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.
