# Re: [R] Summing up matrices in a list

From: Dimitris Rizopoulos <dimitris.rizopoulos_at_med.kuleuven.ac.be>
Date: Thu 17 Mar 2005 - 04:09:35 EST

yes, but I think this works only if the list contains 2 matrices, isn't it?

> mylist <- list(matrix(1:6, 2), matrix(7:12, 2), matrix(13:18, 2))
> do.call("+", mylist)
Error in do.call("+", mylist) : operator needs one or two arguments

Best,
Dimitris

• Original Message ----- From: "Adaikalavan Ramasamy" <ramasamy@cancer.org.uk> To: "Vicky Landsman" <msvika@mscc.huji.ac.il> Cc: "R-help" <r-help@stat.math.ethz.ch> Sent: Wednesday, March 16, 2005 5:32 PM Subject: Re: [R] Summing up matrices in a list

> mylist <- list( matrix(1:6, nc=3), matrix(7:12, nc=3) )
> do.call("+", mylist)
> [,1] [,2] [,3]
> [1,] 8 12 16
> [2,] 10 14 18
>
>
>
> 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,
>> Vicky Landsman.
>> [[alternative HTML version deleted]]
>>
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>
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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 04:23:57 2005

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