[R] sustraction of two vectors of matrix

[Jeff Newmiller]

or with no loops and no preallocation:

bb <- aa[ , 2:5 ] - aa[ , 1:4 ]


On December 5, 2018 8:51:16 AM PST, Rui Barradas <ruipbarradas using sapo.pt> wrote:
>Hello,
>
>1) You don't need matrix(outer(etc)), outer already returns a matrix.
>2) You need to create bb first.
>
>aa <- outer(0:3, 0:4, function(x,y) x + y*2)
>
>bb <- matrix(nrow = 4, ncol = 4)
>
>for(i in 1:4){
>   for(j in 2:5){
>     bb[i, j - 1] <- aa[i, j] - aa[i, j - 1]
>   }
>}
>
>bb
>
>
>Hope this helps,
>
>Rui Barradas
>
>
>Às 14:30 de 05/12/2018, malika yassa via R-help escreveu:
>> helloplease   I want to make a sustration of two vectors of a matrix
>> i have this program
>> 
>> aa<-matrix(outer(0:3,0:4,function(x,y) x+y*2),nrow=4,ncol=5)
>> for(i in 1:4)
>> + {for(j in 2:5)
>> + {bb[i,j-1]=aa[i,j]-aa[i,j-1]
>> + }
>> + }
>> at the end i obtain the bb=matrix( nrow=4,ncol=4)
>> but i cann't obtain this matrix
>> thank you very much
>> 
>> 
>> 
>> 
>> 	[[alternative HTML version deleted]]
>> 
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>______________________________________________
>R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>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.

-- 
Sent from my phone. Please excuse my brevity.