R help - May 2006 - Concatenating data frame

Hello, I have searched through the R-help archive and find that the easiest 
way to concatenate data records in a dataframe is to use rbind()


I know we can do that using rbind, but it is slow when we are doing rbind 
thousands of times to a growing list, each time adding one or two records to 
the ever growing existing data because in

existingRecords<-rbind(existingRecords, aNewRecordToBeAdded),

I am making a copy of the data each time rbind is called!

Is there a way to avoid these data copying?


Thank you in advance!

Charles

Put the intermediate results in a list and then use do.call:

result <- list()
for (i in 1:100){
    result[[i]] <- data.frame(id=sample(letters,1), value=i)
}
newDataFrame <- do.call('rbind', result)




On 5/10/06, Charles Cheung <boom2k1@hotmail.com>
wrote:
>
> Hello, I have searched through the R-help archive and find that the
> easiest
> way to concatenate data records in a dataframe is to use rbind()
>
>
> I know we can do that using rbind, but it is slow when we are doing rbind
> thousands of times to a growing list, each time adding one or two records
> to
> the ever growing existing data because in
>
> existingRecords<-rbind(existingRecords, aNewRecordToBeAdded),
>
> I am making a copy of the data each time rbind is called!
>
> Is there a way to avoid these data copying?
>
>
> Thank you in advance!
>
> Charles
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>


--
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What the problem you are trying to solve?

	[[alternative HTML version deleted]]

And adding to Jim's solution, you may be able to further improve the speed 
of your code by pre-allocating the list size i.e

result <- vector("list",100)
for (i in 1:100){
  result[[i]] <- data.frame(id=sample(letters,1), value=i)
}
newDataFrame <- do.call('rbind', result)

Cheers

Francisco
>From: "jim holtman" <jholtman at gmail.com>
>To: "Charles Cheung" <boom2k1 at hotmail.com>
>CC: r-help at stat.math.ethz.ch
>Subject: Re: [R] Concatenating data frame
>Date: Wed, 10 May 2006 19:02:15 -0400
>
>Put the intermediate results in a list and then use do.call:
>
>result <- list()
>for (i in 1:100){
>     result[[i]] <- data.frame(id=sample(letters,1), value=i)
>}
>newDataFrame <- do.call('rbind', result)
>
>
>
>
>On 5/10/06, Charles Cheung <boom2k1 at hotmail.com> wrote:
> >
> > Hello, I have searched through the R-help archive and find that the
> > easiest
> > way to concatenate data records in a dataframe is to use rbind()
> >
> >
> > I know we can do that using rbind, but it is slow when we are doing 
>rbind
> > thousands of times to a growing list, each time adding one or two 
>records
> > to
> > the ever growing existing data because in
> >
> > existingRecords<-rbind(existingRecords, aNewRecordToBeAdded),
> >
> > I am making a copy of the data each time rbind is called!
> >
> > Is there a way to avoid these data copying?
> >
> >
> > Thank you in advance!
> >
> > Charles
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide!
> > http://www.R-project.org/posting-guide.html
> >
>
>
>
>--
>Jim Holtman
>Cincinnati, OH
>+1 513 646 9390 (Cell)
>+1 513 247 0281 (Home)
>
>What the problem you are trying to solve?
>
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide! 
>http://www.R-project.org/posting-guide.html