Hi guys, I am trying to write a function that allows me to perform specific transformations to each element of a 2 by 2 matrix to generate a 3 by 3 matrix. Input into function-2 by 2 matrix Output from function -3 by 3 matrix For example: # a is my original 2 by 2 matrix #b is my new 3 by 3 matrix set.seed(2) a=matrix(rnorm(4),ncol=2) #let's say these are the transformations i wish to perform b[1,1]=a[1,1]+1 b[1,2]=a[2,1]*a[2,2] b[1,3]=a[2,2]+a[1,1] b[2,1]=a[1,1]-5 b[2,2]=sqrt(a[2,2]) b[2,3]=a[1,1]/a[2,2] b[3,1]=a[2,2]-3 b[3,2]=a[1,1]*[a[1,2]+a[2,2]) b[3,3]=sqrt(a[1,1])/a[1,2]) Thanks. Cheers, B -- View this message in context: http://r.789695.n4.nabble.com/specific-matrix-element-tranformation-tp4640550.html Sent from the R help mailing list archive at Nabble.com.
Hi guys,
After a long while I came up with this :
set.seed(2)
a<-matrix(rnorm(4),ncol=2)
abc<-function(a)
{
b=matrix(NA,nrow=3,ncol=3)
b[1,1]=a[1,1]+1
b[1,2]=a[2,1]*a[2,2]
b[1,3]=a[2,2]+a[1,1]
b[2,1]=a[1,1]-5
b[2,2]=sqrt(a[2,2])
b[2,3]=a[1,1]/a[2,2]
b[3,1]=a[2,2]-3
b[3,2]=a[1,1]*(a[1,2]+a[2,2])
b[3,3]=sqrt(a[1,1])/a[1,2]
return(b=matrix(c(b[1,1],b[1,2],b[1,3],b[2,1],b[2,2],b[2,3],
b[3,1],b[3,2],b[3,3]),ncol=3))
}
How can I improve on it?
Cheers,
B
--
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On Aug 16, 2012, at 8:39 PM, bantex wrote:> Hi guys, > > After a long while I came up with this : > > set.seed(2) > a<-matrix(rnorm(4),ncol=2) > abc<-function(a) > { > b=matrix(NA,nrow=3,ncol=3) > b[1,1]=a[1,1]+1 > b[1,2]=a[2,1]*a[2,2] > b[1,3]=a[2,2]+a[1,1] > b[2,1]=a[1,1]-5 > b[2,2]=sqrt(a[2,2]) > b[2,3]=a[1,1]/a[2,2] > b[3,1]=a[2,2]-3 > b[3,2]=a[1,1]*(a[1,2]+a[2,2]) > b[3,3]=sqrt(a[1,1])/a[1,2] > > # return(b=matrix(c(b[1,1],b[1,2],b[1,3],b[2,1],b[2,2],b[2,3], > # b[3,1],b[3,2],b[3,3]),ncol=3))return(b)> } > > How can I improve on it? > > Cheers, > B > > > > > -- > View this message in context: http://r.789695.n4.nabble.com/specific-matrix-element-tranformation-tp4640550p4640554.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > 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.David Winsemius, MD Alameda, CA, USA
Thanks David. I have actually 1 more question. How do I assign a name to the output created by this function? Cheers, B -- View this message in context: http://r.789695.n4.nabble.com/specific-matrix-element-tranformation-tp4640550p4640680.html Sent from the R help mailing list archive at Nabble.com.
On Aug 17, 2012, at 6:04 PM, bantex wrote:> Thanks David. I have actually 1 more question. How do I assign a > name to the > output created by this function? >abc_ret <- abc(...)> -- > View this message in context: http://r.789695.n4.nabble.com/specific-matrix-element-tranformation-tp4640550p4640680.html > Sent from the R help mailing list archive at Nabble.com.Rhelp is a mailing list. It is NOT Nabble. You are asked in the Posting Guide to include context.>>>>>>>>>>>>>>>>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html>>>>>>>>>>>>>>> David Winsemius, MD Alameda, CA, USA
Please do include context. "name assignment" can mean a few things: i) Adding a "name" attribute can be done with names(x) <- _whatever_ ii) Assigning to an object name should be done outside the function, not within it: x <- myLongFunc(...) Cheers, Michael On Fri, Aug 17, 2012 at 9:04 PM, bantex <bantexmutation at hotmail.com> wrote:> Thanks David. I have actually 1 more question. How do I assign a name to the > output created by this function? > > Cheers, > B > > > > -- > View this message in context: http://r.789695.n4.nabble.com/specific-matrix-element-tranformation-tp4640550p4640680.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > 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.