Re: [R] Create a new var reflecting the order of subjects in existing var

From: Nguyen Dinh Nguyen <n.nguyen_at_garvan.org.au>
Date: Mon 02 Apr 2007 - 06:51:02 GMT


Dear R users,

Followings are summary the solutions for my question. All the way to Roma!

But vote #1 for Jim, the simplest solution.

Thank you all of you for yours quick response

Regards

Nguyen  

# I have a data set sth like this:
 

set.seed(123);dat <- data.frame(ID= c(rep(1,2),rep(2,3), rep(3,3), rep(4,4), rep(5,5)),

                  var1 =rnorm(17, 35,2),

                  var2=runif(17,0,1))

 

# I would like to create a new var in dat which reflects the order of each
subject (ID), like this

# ID var1 var2 IDorder

# 1 1 33.87905 0.02461368 1

# 2 1 34.53965 0.47779597 2

# 3 2 38.11742 0.75845954 1

# 4 2 35.14102 0.21640794 2

# 5 2 35.25858 0.31818101 3

# 6 3 38.43013 0.23162579 1

# 7 3 35.92183 0.14280002 2

# 8 3 32.46988 0.41454634 3

# 9 4 33.62629 0.41372433 1

# 10 4 34.10868 0.36884545 2

# 11 4 37.44816 0.15244475 3

# 12 4 35.71963 0.13880606 4

# 13 5 35.80154 0.23303410 1

# 14 5 35.22137 0.46596245 2

# 15 5 33.88832 0.26597264 3

# 16 5 38.57383 0.85782772 4

# 17 5 35.99570 0.04583117 5
   

##SOLUTIONS
 
# 1st (by Christos Hatzis)

y <- rle(dat$ID) # rle: Run Length Endcoding

dat$IDorder1 <- unlist(sapply(y$lengths, FUN=function(x) seq(1,x)))

dat  

# 2st (by Chaliraos Skiadas)

dat$IDorder2 <- unlist(tapply(dat$ID,factor(dat$ID), function(x)

1:length(x)),use.names=FALSE)

dat  

#3rd (Jim Holtman)

dat$IDorder3 <- ave(dat$ID, dat$ID, FUN=seq)  

#4 (Gabor Grothendieck) Assuming the ID's are contiguous

dat <- transform(dat, IDorder3 = seq(ID) - match(ID, ID) + 1)

dat  

#5th (Milton Cezar Ribeiro)

ID.freq<-table(dat$ID)

ID.freq

ID.seq<-NULL

for (i in names(ID.freq))

 {

 ID.seq<-c(ID.seq,seq(from=1, to=ID.freq[i], by=1))

 }

dat$ID.seq<-ID.seq

dat

# END
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