It this what you are looking for:
> set.seed(1)
> # create range for each possible class
> # 'name' the values so you can use them in the 'sapply' function
> lows<-c(a=1, b=2, c=3, d=4, e=5)
> highs<-c(a=5, b=6, c=7, d=8, e=9)
>
> # data values
> vals<-sample(1:10,100,replace=T)
>
> #classes
> classes<-sample(letters[1:5],100,replace=T)
>
> # split the data so that you retain the 'classes' name
> x.split <- split(vals, classes)
> percentage <- sapply(names(x.split), function(.class){
+ # compute the percentage based on 'class'
+ sum((x.split[[.class]] >= lows[.class]) &
+ (x.split[[.class]] <= highs[.class])) /
length(x.split[[.class]]) * 100
+ })
> percentage
a b c d e
50.00000 45.00000 62.50000 54.54545 55.55556
>
On Fri, Jun 4, 2010 at 4:02 PM, Mark Ebbert <mark.ebb...@hci.utah.edu> wrote:
> Dear R gurus,
>
> I am trying perform what I believe will be a pretty simple task, but I'm
> struggling to figure out how to do it. I have two vectors of the same length,
> the first is numeric and the second is factor. I understand that tapply is
> perfect for applying a function to the numeric vector by subsets of the
> factors in the second vector. My issue is trying to make use of two other
> vectors within the custom function I've written for tapply. The two other
> vectors are a high and low value for each subset I am breaking my data into,
> and I want to calculate the percentage of data points that fall into each
> respective range. I will attempt to provide a coherent example:
>
> # create range for each possible class
> lows<-c(1,2,3,4,5)
> highs<-c(5,6,7,8,9)
>
> # data values
> vals<-sample(1:10,100,replace=T)
>
> #classes
> classes<-sample(letters[1:5],100,replace=T)
>
> # Try to calculate percentage of values that fall
> # into the respective range for the given class.
> percentages<-tapply(vals,classes,
> function(i){
> length(i[i>=lows[index] & i<=highs[index]])/length(i) # I
> don't know how to actually keep an index count in tapply, but I'm guessing
> there's a better way.
> })
>
> I really appreciate any help.
>
> ME
> ______________________________________________
> R-help@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.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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