RE: [R] Summing up matrices in a list

From: Marc Schwartz <MSchwartz_at_medanalytics.com>
Date: Thu 17 Mar 2005 - 04:07:48 EST

John,

That is correct. I took the example perhaps too literally, depending upon what Vicky requires. If indeed the data structure is comprised of
>2 matrices, the approach using do.call() will not work.

Thanks for pointing that out. I see that Adai had a similar idea.

Best regards,

Marc

On Wed, 2005-03-16 at 12:00 -0500, John Fox wrote:
> Dear Mark,
>
> I believe that your solution won't work if there are more than two matrices
> to sum.
>
> Regards,
> John
>
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> --------------------------------
>
> > -----Original Message-----
> > From: r-help-bounces@stat.math.ethz.ch
> > [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Marc Schwartz
> > Sent: Wednesday, March 16, 2005 11:30 AM
> > To: Vicky Landsman
> > Cc: R-Help
> > Subject: Re: [R] Summing up matrices in a list
> >
> > On Wed, 2005-03-16 at 18:21 +0200, Vicky Landsman wrote:
> > > Dear all,
> > > I think that my question is very simple but I failed to solve it.
> > > I have a list which elements are matrices like this:
> > >
> > > >mylist
> > > [[1]]
> > > [,1] [,2] [,3]
> > > [1,] 1 3 5
> > > [2,] 2 4 6
> > >
> > > [[2]]
> > > [,1] [,2] [,3]
> > > [1,] 7 9 11
> > > [2,] 8 10 12
> > >
> > > I'd like to create a matrix M<-mylist[[1]]+mylist[[2]]
> > > [,1] [,2] [,3]
> > > [1,] 8 12 16
> > > [2,] 10 14 18
> > >
> > > Is there a way to create M without looping?
> > > Thanks a lot,
> >
> >
> > > do.call("+", mylist)
> > [,1] [,2] [,3]
> > [1,] 8 12 16
> > [2,] 10 14 18
> >
> > See ?do.call for more information.
> >
> > HTH,
> >
> > Marc Schwartz
> >
> > ______________________________________________
> > 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



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 Received on Thu Mar 17 04:22:01 2005

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