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
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