[R] scoping issues?
Jan T. Kim
jtk at cmp.uea.ac.uk
Thu Dec 8 19:14:09 CET 2005
On Thu, Dec 08, 2005 at 06:47:05AM -0500, tom wright wrote:
> Can anyone please help me understand whats happening here?
> Thanks
> Tom
>
> getAmpRatio<-function(v_amps){
> #calculates the amplitude ratios between the 3 largest amps and the
> rest
> bigamp<-0
> map<-rep(TRUE,length(v_amps))
>
> for(iLoc in 1:3){
> bigamp<-bigamp+max(v_amps)
> map[which.max(v_amps)]<-FALSE
> v_amps<-v_amps[map]
> map<-rep(TRUE,length(v_amps))
> }
> browser()
> return(bigamp/mean(v_amps))
> }
>
> amps<-c(1,2,3,3,3,2,1)
> getAmpRatio(amps)
>
> Browse[1]> v_amps
> [1] 1 1 2 2 1
> Browse[1]> c(amps[1],amps[2],amps[3],amps[7],amps[8])
> [1] 1 1 2 2 1
> Browse[1]> mean(v_amps)
> [1] 1.4
This computes the mean of the set {1, 1, 2, 2, 1}, which is 7 / 5 = 1.4
> Browse[1]> mean(amps[1],amps[2],amps[3],amps[7],amps[8])
> [1] 1
This computes the mean of amps[1], i.e. of the set {1}, which is 1 / 1 = 1.
The remaining parameters are matched to the special variable length
formal parameter of the mean function, which, upon eventual dispatch
to mean.default are basically ignored, as far as I see.
Perhaps, you meant
mean(c(amps[1], amps[2], amps[3], amps[7], amps[8]))
which effectively calls mean with one argument of length 5, as opposed
to 5 arguments of length 1, as your call does.
Best regards, Jan
--
+- Jan T. Kim -------------------------------------------------------+
| email: jtk at cmp.uea.ac.uk |
| WWW: http://www.cmp.uea.ac.uk/people/jtk |
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