[R] function return

[David Winsemius]

On Jul 22, 2010, at 5:34 PM, David Winsemius wrote:

>
> On Jul 22, 2010, at 5:27 PM, Daniel Hocking wrote:
>
>> I am sorry if this question is vague or uninformed.  I am just
>> learning R and struggling.  I am using the book Hierarchical Modeling
>> and Inference in Ecology and they provide examples of R code.  I have
>> the following code from the book but when I run it I don't get any
>> output.  I cannot get the values of 'out' to show up.  Basically, I
>> just want to see my estimates for b0, b1, b2, and b3.  Any time  
>> that I
>> have used or see function( ) there have been arguments and I just  
>> call
>> for the value of the function.  In this case there doesn't seem to be
>> a value for the function.  Any help would be appreciated.
>
> You have defined a function that has no arguments. You should be  
> typing  this at the console:
>
> panel3pt1.fn()
>
> I get an error because there is no such file on my machine and you  
> have not provided a link to an accessible copy.

If you go to their website
http://www.mbr-pwrc.usgs.gov/pubanalysis/roylebook/chapters.htm
... and:
a) download the .Rd file and the similarly named .csv file referenced  
by that function to your working directory
b) change the extension of the .csv file to match the function reference
c) add   , sep=","    to the read.table call
d) then do what I said above ....

 > panel3pt1.fn()  # Voilà !!

$minimum
[1] 100.887223663

$estimate
[1] -0.542213281782  1.847343506809 -1.060864239423  0.646910762031

$gradient
[1] 2.34905428442e-05 3.14549972521e-05 6.51961177771e-05  
4.88853402203e-05

$hessian
                [,1]           [,2]           [,3]            [,4]
[1,] 33.38181500113 15.26441629493  27.8670270859   6.61193837459
[2,] 15.26441629493 27.86699589010  30.5057286674  -9.66977848175
[3,] 27.86702708591 30.50572866744  52.5892374981 -12.50448633528
[4,]  6.61193837459 -9.66977848175 -12.5044863353  34.09027300450

$code
[1] 1

$iterations
[1] 16

-- 
> David.
>
>
>>
>> Thanks,
>> Dan
>>
>>
>> `panel3pt1.fn` <-
>> function(){
>>
>> source("utilfns.Rd")
>>
>> data<- read.table("wtmatrix.txt",header=T,na.strings=T)
>> elev<-data[,"elev"]
>> forest<-data[,"forest"]
>> elev<-scale(elev,center=TRUE)
>> forest<-scale(forest,center=TRUE)
>> pamat<-data[,c("y.1","y.2","y.3")]
>> z<-pamat[,1]
>> M<-length(z)
>>
>>
>> lik<-function(parms){
>>    b0<-parms[1]
>>    b1<-parms[2]
>>    b2<-parms[3]
>>    b3<-parms[4]
>>    ones<-rep(1,M)
>>    ### Compute binomial success probabilities
>>    probs<-expit(b0*ones+b1*elev+b2*(elev^2)+b3*forest)
>>    lik<-rep(0,length(z))
>>    ### evaluate log of binomial pmf
>>    tmp<-log(dbinom(z,1,probs))
>>    ### substitute 0 for missing values
>>    lik[!is.na(z)]  <-  tmp[!is.na(z)]
>>    lik<-  -1*sum(lik)
>>    return(lik)
>> }
>>
>> out <- nlm(lik,c(0,0,0,0),hessian=TRUE)
>>
>> return(out)
>>
>>
>> }
>>
>> ------------------------------------------------------------------------------------
>> Daniel J. Hocking
>> 122 James  Hall
>> Department of Natural Resources & the Environment
>> University of New Hampshire
>> Durham, NH 03824
>>
>> dhocking at unh.edu
>> http://sites.google.com/site/danieljhocking/
>> www.hockingphotography.smugmug.com
>>
>> "Without data, all you are is just another person with an opinion."
>> -------------------------------------------------------------------------------------
>>
>>
>>
>>
>>
>>
>>
>> 	[[alternative HTML version deleted]]
>>
>> ______________________________________________
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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.
>
> David Winsemius, MD
> West Hartford, CT
>
> ______________________________________________
> R-help at 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.

David Winsemius, MD
West Hartford, CT