Re: [R] a more elegant way to get percentages?

From: Christos Hatzis <christos.hatzis_at_nuverabio.com>
Date: Thu, 13 Mar 2008 09:54:11 -0400

Monica,

You can try the following:

> x.tot <- aggregate(x$val, by=list(total=x$locat), 'sum')
> x.tot

  total x

1     a  5
2     b 20
3     c 40
4     d 30

> cbind(x, perc=x$val/rep(x.tot$x, table(x$locat)) * 100)
locat val perc 1 a 5 100.00000 2 b 5 25.00000 3 b 15 75.00000 4 c 5 12.50000 5 c 20 50.00000 6 c 5 12.50000 7 c 10 25.00000 8 d 5 16.66667 9 d 15 50.00000 10 d 10 33.33333

-Christos

> -----Original Message-----
> From: r-help-bounces_at_r-project.org
> [mailto:r-help-bounces_at_r-project.org] On Behalf Of Monica Pisica
> Sent: Thursday, March 13, 2008 9:36 AM
> To: r-help_at_r-project.org
> Subject: [R] a more elegant way to get percentages?
>
>
> Hi,
>
> I am trying to get percentages in a more elegant way. I have
> a data.frame with locations and values (counts) of species at
> that location. Each location is repeated for each species i
> have values for and i would like to get percentages of each
> species at that location. I am not sure if i am clear in my
> explanations so i will paste my code below:
>
> #####################
>
> > x
> locat val
> 1 a 5
> 2 b 5
> 3 b 15
> 4 c 5
> 5 c 20
> 6 c 5
> 7 c 10
> 8 d 5
> 9 d 15
> 10 d 10
> > loc1 <- x$locat
> > n <- length(loc1)
> > locuniq1 <- unique(loc1)
> > m <- length(locuniq1)
> > counts <- seq(1:m)
> >
> > for (i in 1:m) {
> + count <- 0
> + for (j in 1:n) {
> + if (loc1[j]==locuniq1[i]) count <- count+1 counts[i] <- count } }
> >
> > percent1 <- rep(0,n)
> > j <- 0
> > for (i in 1:m) {
> +
> + b <- x[(j+1):(j+counts[i]),]
> + total <- sum(b$val)
> + percent1[(j+1):(j+counts[i])] <- round(apply(as.matrix(b$val), 1,
> + function(x) {x*100/total}),2) j = j+counts[i] }
> > x1 <- cbind(x, percent1) # this is the result i want
> > x1
> locat val percent1
> 1 a 5 100.00
> 2 b 5 25.00
> 3 b 15 75.00
> 4 c 5 12.50
> 5 c 20 50.00
> 6 c 5 12.50
> 7 c 10 25.00
> 8 d 5 16.67
> 9 d 15 50.00
> 10 d 10 33.33
> >
> ################
>
> I am wondering if there is any way to do it more efficiently,
> much more that the first loop which gives how many times each
> location is present in the data.frame is slow if you have a
> larger data.frame and not only 10 rows.
>
> Thanks for any input and sorry if the email is on the long side,
>
> Monica
>
>
> _________________________________________________________________
> [[elided Hotmail spam]]
>
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>
>



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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. Received on Thu 13 Mar 2008 - 16:45:09 GMT

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