Get a percent variable based on group

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

aggregate(iris$percent, by=list(iris$Species),
FUN=sum, na.rm=TRUE)

this last command should return 100% for each specie, not the following values: 
Group.1???????? x
1???? setosa 0.2855676
2 versicolor 0.3386195
3? virginica 0.3758129


________________________________
From: karine.charlebois at outlook.com
To: smartpink111 at yahoo.com
Subject: RE: [R] Get a percent variable based on group
Date: Tue, 15 Jan 2013 22:13:27 -0500


No, it is not. I need a new column with these values.

Karine


> Date: Tue, 15 Jan 2013 19:11:22 -0800
> From: smartpink111 at yahoo.com
> Subject: Re: [R] Get a percent variable based on group
> To: karine.charlebois at outlook.com
> CC: r-help at r-project.org
> 
> 
> 
> 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]]
> 
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