[R] Get a percent variable based on group

[arun]

HI,

Not sure if this is what you meant.
tapply(iris$Sepal.Length,iris$Species,FUN=function(x) sum(x)/sum(iris$Sepal.Length)*100)
 #  setosa versicolor  virginica 
 # 28.55676   33.86195   37.58129 
A.K.


----- Original Message -----
From: Karine Charlebois <karine.charlebois at outlook.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc: 
Sent: Tuesday, January 15, 2013 9:30 PM
Subject: [R] Get a percent variable based on group

Dear all, I'd like to get a percentage variable based on a group, but without creating a new data frame. 
For example:
data(iris)

iris$percent <-unlist(tapply(iris$Sepal.Length,iris$Species,function(x) x/sum(x, na.rm=TRUE)))

This does not work, I should have only three standard values, respectively for setosa, versicolor, and virginica. How can I do this?

MANY THANKS,

Karine 
                          
    [[alternative HTML version deleted]]

______________________________________________
R-help at 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.