R help - Jan 2013 - Object created within a function disappears after the function is run

Dear R-helpers,

I have run the code below which I expected to make an object called dd1,
but that object does not exist.

So, in summary, my problem is that my function is meant to make an object
(dd1), and it does indeed make that object (I know that the last line of
the function prints it out) but then, after the function has run, the
object has disappeared.

It's late on a Friday so I may be overlooking something obvious, but I'd
appreciate your help if you can see what I'm doing wrong.

Many thanks,

Mark Na



rm(list=ls())

#LOAD package, data, and keep clean copies of data
library(reshape2); library(MuMIn);library(AICcmodavg)
birdmatrix<-read.csv("birdmatrix.csv",stringsAsFactors=FALSE);
birdmatrixclean<-birdmatrix
habitatmatrix<-read.csv("habitatmatrix.csv",stringsAsFactors=FALSE);
habitatmatrixclean<-habitatmatrix
traits<-read.csv("traits.csv",stringsAsFactors=FALSE);
traitsclean<-traits
birdhabitat<-merge(birdmatrix,habitatmatrix,by="SARBASINYEAR")
#merge bird
and habitat data
data<-birdhabitat; data$SAR<-substr(data$SARBASINYEAR,1,3) #convenience;
create SAR variable

#make a FUNCTION to combine variables into models
dredgeit<-function(lm1){
dd1<-dredge(lm1,eval=FALSE) #create all possible combinations
dd1<-gsub("formula = ","",dd1,fixed=TRUE) #delete
characters
dd1<-gsub(" + 1","",dd1,fixed=TRUE) #delete characters
dd1#inspect model formulae
}

lm1<-lm(data$BiRich.o~log(data$HaArea,10)+log(data$HaPeri,10)) #saturated
submodel
dredgeit(lm1)

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Hi Sarah, that works perfectly, thank you!

Mark Na


On Fri, Jan 18, 2013 at 5:23 PM, Sarah Goslee
<sarah.goslee@gmail.com>wrote:
> Hi,
>
> You need to assign the result of the function to an object:
>
> dd1 <- dredgeit(lm1)
>
> On Fri, Jan 18, 2013 at 6:17 PM,  <mtb954@gmail.com> wrote:
> > Dear R-helpers,
> >
> > I have run the code below which I expected to make an object called
dd1,
> > but that object does not exist.
> >
> > So, in summary, my problem is that my function is meant to make an
object
> > (dd1), and it does indeed make that object (I know that the last line
of
> > the function prints it out) but then, after the function has run, the
> > object has disappeared.
> >
> > It's late on a Friday so I may be overlooking something obvious,
but I'd
> > appreciate your help if you can see what I'm doing wrong.
> >
> > Many thanks,
> >
> > Mark Na
> >
> >
> >
> > rm(list=ls())
> >
> > #LOAD package, data, and keep clean copies of data
> > library(reshape2); library(MuMIn);library(AICcmodavg)
> >
birdmatrix<-read.csv("birdmatrix.csv",stringsAsFactors=FALSE);
> > birdmatrixclean<-birdmatrix
> >
habitatmatrix<-read.csv("habitatmatrix.csv",stringsAsFactors=FALSE);
> > habitatmatrixclean<-habitatmatrix
> > traits<-read.csv("traits.csv",stringsAsFactors=FALSE);
> traitsclean<-traits
> >
birdhabitat<-merge(birdmatrix,habitatmatrix,by="SARBASINYEAR")
#merge
> bird
> > and habitat data
> > data<-birdhabitat; data$SAR<-substr(data$SARBASINYEAR,1,3)
#convenience;
> > create SAR variable
> >
> > #make a FUNCTION to combine variables into models
> > dredgeit<-function(lm1){
> > dd1<-dredge(lm1,eval=FALSE) #create all possible combinations
> > dd1<-gsub("formula = ","",dd1,fixed=TRUE)
#delete characters
> > dd1<-gsub(" + 1","",dd1,fixed=TRUE) #delete
characters
> > dd1#inspect model formulae
> > }
> >
> > lm1<-lm(data$BiRich.o~log(data$HaArea,10)+log(data$HaPeri,10))
#saturated
> > submodel
> > dredgeit(lm1)
> >
> --
> Sarah Goslee
> http://www.functionaldiversity.org
>
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