[R] reshaping data
ruipbarradas at sapo.pt
Wed Jul 25 07:01:10 CEST 2012
Try the following.
# We are going to use this twice
sl <- split(long, long$id)
# Remove groups with only one row
l2 <- lapply(sl, function(x) if(nrow(x) > 1) x)
l2 <- do.call(rbind, l2)
# Create a new variable
l3 <- lapply(sl, function(x) cbind(x, NEW_VARIABLE=seq_len(nrow(x))))
l3 <- do.call(rbind, l3)
Hope this helps,
Em 25-07-2012 01:59, AC Del Re escreveu:
> I am trying to reshape data from a long to wide format but have a specific
> task that I cannot get to output properly.
> # SAMPLE DATA;
> id <- c(1,2,2,3,3,3)
> time <-c(0,0,5, 0, 2, 10)
> x <- rnorm(length(id))
> long <- data.frame(id,time,x)
> # To reshape, I would like to exclude 'id' values that have NO duplicate
> (i.e., remove
> # id=1 in this case). My attempts failed because the functions removes the
> first value of each id (and I would like to preserve them if length of each
> unique id >1), e.g.:
> junk <- long[duplicated(long$id),] # REMOVES TOO MANY ROWS!
> junk <-subset(long, seq(id) - match(id,id) >0) # SAME
> Essentially, I would like to preserve all values of an id with more than
> one row. Any ideas are much appreciated.
> In addition, is there an easy way to create a new variable based on the
> number of instances of each id (in the long dataset)? e.g.
> id time x NEW_VARIABLE
> 1 1 0 -0.03921791 1
> 2 2 0 -1.07869262 1
> 3 2 5 1.73442621 2
> 4 3 0 -0.64356207 1
> 5 3 2 1.19691074 2
> 6 3 10 0.62035225 3
> Thank you,
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