Fast Normalize by Group
Hello, If yopu want one value per group use tapply(), if you want one value per value of x use ave() tapply(x, group, FUN = function(.x) .x/sum(.x)) ave(x, group, FUN = function(.x) .x/sum(.x)) Hope this helps, Rui Barradas Em 29-11-2012 18:55, Noah Silverman escreveu:
Hi,
I have a very large data set (aprox. 100,000 rows.)
The data comes from around 10,000 "groups" with about 10 entered per group.
The values are in one column, the group ID is an integer in the second column.
I want to normalize the values by group:
for(g in unique(groups){
x[group==g] / sum(x[group==g])
}
This works find in a loop, but is slow. Is there a faster way to do this?
Thanks!
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