Is this what you want?
> x <- read.table(textConnection("Index A
+ 1 1
+ 1 2
+ 1 3
+ 2 4
+ 2 3
+ 3 7
+ 3 9
+ 3 3
+ 3 1"), header=TRUE)
> data.frame(x, value=ave(x$A, x$Index, FUN=function(z) z / sum(z)))
Index A value
1 1 1 0.1666667
2 1 2 0.3333333
3 1 3 0.5000000
4 2 4 0.5714286
5 2 3 0.4285714
6 3 7 0.3500000
7 3 9 0.4500000
8 3 3 0.1500000
9 3 1 0.0500000
On Feb 1, 2008 6:19 PM, YIHSU CHEN <[EMAIL PROTECTED]> wrote:
> Dear R users
>
> I wonder if there is a quick way to calculate the ratio/fraction of a
> list/data frame. For example, if I have a data frame with two fields:
> "Index" and "A". I would like to know the fractions of A's within the same
> "Index". That is, for Index =1, three fractions will be "1/(1+2+3)=0.17",
> "2/(1+2+3)=0.33", and "3/1+2+3=0.5". Likewise for Index =2 and Index 3.
> So, I then generate a new vector of 0.17, 0.33, 0.5... ,etc.
>
>
> Index A 1 1 1 2 1 3 2 4 2 3 3 7 3 9 3 3 3 1
>
> Thank you so much
>
> Yihsu
>
> [[alternative HTML version deleted]]
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
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