On 2012-07-24 22:01, Rui Barradas wrote:
Hello,
Try the following.
# We are going to use this twice
sl <- split(long, long$id)
# Remove groups with only one row
l2 <- lapply(sl, function(x) if(nrow(x) > 1) x)
l2 <- do.call(rbind, l2)
l2
# Create a new variable
l3 <- lapply(sl, function(x) cbind(x, NEW_VARIABLE=seq_len(nrow(x))))
l3 <- do.call(rbind, l3)
l3
Hope this helps,
Rui Barradas
Another way is to use ave() to construct a
variable (I call it z below) to indicate
which rows to keep. We'll also construct
a variable 'count' to satisfy the additional
request.
long1 <- transform(long,
count= ave(id, id,
FUN = function(x) seq_len(length(x))),
z = ave(id, id, FUN = length))
long2 <- subset(long1, z > 1, -z)
Peter Ehlers
Em 25-07-2012 01:59, AC Del Re escreveu:
Hi,
I am trying to reshape data from a long to wide format but have a specific
task that I cannot get to output properly.
# SAMPLE DATA;
id <- c(1,2,2,3,3,3)
time <-c(0,0,5, 0, 2, 10)
x <- rnorm(length(id))
long <- data.frame(id,time,x)
# To reshape, I would like to exclude 'id' values that have NO duplicate
(i.e., remove
# id=1 in this case). My attempts failed because the functions removes the
first value of each id (and I would like to preserve them if length of each
unique id >1), e.g.:
junk <- long[duplicated(long$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,
AC
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