Summing up matrices in a list
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 at stat.math.ethz.ch [mailto:r-help-bounces at 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
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