Hi,
I need a bit of guidance with the sapply function. I've read the help
page, but am still a bit unsure how to use it.
I have a large data frame with about 100 columns and 30,000 rows. One
of the columns is "group" of which there are about 2,000 distinct "groups".
I want to normalize (sum to 1) one of my variables per-group.
Normally, I would just write a huge "for each" loop, but have read that
is hugely inefficient with R.
The old way would be (just an example, syntax might not be perfect):
for (group in data$group){
for (score in data[data$group == group]){
new_score <- score / sum(data$score[data$group==group])
}
}
How would I simplify this with sapply?
Thanks!
--
Noah
______________________________________________
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.
