Re: [R] Matrix operations in a list

From: Dimitris Rizopoulos <dimitris.rizopoulos_at_med.kuleuven.be>
Date: Tue 23 Jan 2007 - 15:47:49 GMT

you need the 'SIMPLIFY' argument of mapply(), i.e.,

mapply("%*%", a, b, SIMPLIFY = FALSE)

I hope it helps.

Best,
Dimitris



Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium

Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm

>I have matrices stored within a list like something as follows:
>
> a <- list(matrix(rnorm(50), ncol=5), matrix(rnorm(50), ncol=5))
> b <- list(matrix(rnorm(50), nrow=5), matrix(rnorm(50), nrow=5))
>
> I don't recall how to perform matrix multiplication on each list
> element
> such that the result is a new list
>
> result <- list(a[[1]]%*%b[[1]], a[[2]]%*%b[[2]])
>
> I think I'm close with mapply(), but I'm doing something silly
>
> mapply('%*%', a,b)
>
> Thanks.
> Harold
>
>
> [[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. Received on Wed Jan 24 02:59:56 2007

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