[R] Matrix element-by-element multiplication

Steven Yen syen04 at gmail.com
Thu Jan 8 00:05:46 CET 2015


I like to multiple the first and second column of a 10 x 3 matrix by 
100. The following did not work. I need this in an operation with a 
much larger scale. Any help?

aa<-matrix(1:30,nrow=10,ncol=3); aa
bb<-matrix(c(100,100,1),nrow=1,ncol=3); bb
dim(aa)
dim(bb)
aa*bb

Results:

 > aa<-matrix(1:30,nrow=10,ncol=3); aa
       [,1] [,2] [,3]
  [1,]    1   11   21
  [2,]    2   12   22
  [3,]    3   13   23
  [4,]    4   14   24
  [5,]    5   15   25
  [6,]    6   16   26
  [7,]    7   17   27
  [8,]    8   18   28
  [9,]    9   19   29
[10,]   10   20   30
 > bb<-matrix(c(100,100,1),nrow=1,ncol=3); bb
      [,1] [,2] [,3]
[1,]  100  100    1
 > dim(aa)
[1] 10  3
 > dim(bb)
[1] 1 3
 > aa*bb
Error in aa * bb : non-conformable arrays

 >



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