Hi,
May be you can also use ?aggregate():
x1<-aggregate(x,list(x),function(x) seq_along(x)-1)
# Group.1??????????????????????????????????????????????????????????? x
#1?????? a????????????????????????????????????????? 0, 1, 2, 3, 4, 5, 6
#2?????? b???????????????????????????????????????????? 0, 1, 2, 3, 4, 5
#3?????? c??????????????????????????????????? 0, 1, 2, 3, 4, 5, 6, 7, 8
#4?????? d???????????????????????????????? 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
#5?????? e 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17
A.K.
----- Original Message -----
From: PIKAL Petr <petr.pikal at precheza.cz>
To: Jon Toledo <tintin_jb at hotmail.com>; "r-help at r-project.org" <r-help at r-project.org>
Cc:
Sent: Tuesday, September 4, 2012 7:07 AM
Subject: Re: [R] Create a function to number each repeated visit or measurements
Hi
You did not provided any suitable data.
x<-sort(sample(letters[1:5], 50, rep=T))
unlist(lapply(split(x,x), function(x) (1:length(x))-1))
gives you a vector of indices from 0 to n for sorted vector x.
Regards
Petr
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Jon Toledo
Sent: Tuesday, September 04, 2012 7:59 AM
To: r-help at 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
J ToledoUPennUSA
??? [[alternative HTML version deleted]]