[R] Multiplying each row of a big matrix with a vector

[Attiglah, Mama]

Ret= matrix(sample( 1:1000, 500*9), nrow=500, ncol=9)


Pos= c(  2593419  ,2130220,  6198197,  1673888,  1980000 , 1784732 ,
2052120 ,-7490228 ,-5275000)


Solution = Ret * matrix( rep(Pos, 500), nrow=500, byrow=TRUE)
Use the element-wise multiplication rather than a matrix multiplication.
Hope this helps.
Mama 

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Mama Attiglah, PhD
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-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Megh Dal
Sent: 30 January 2008 07:20
To: r-help at stat.math.ethz.ch
Subject: [R] Multiplying each row of a big matrix with a vector

I have a big matrix 'ret'. I want to multiply each row of it with a 2nd
vector 'pos', resulting result, I want to save in a vector named 'port'.
I wrote following code:
   
  > pos
[1]  2593419  2130220  6198197  1673888  1980000  1784732  2052120
-7490228 -5275000

   
  > dim(ret)
[1] 500   9

  > fu    # user defined function
function(x)
   {
    fu = x %*% t(pos)
   }
port = apply(ret, 1, fu)

  > dim(port)
[1]  81 500

  My desire is to get port as a vector with length 500. However I am not
getting that?
   
  Can anyone tell me how to correct that? 
   
  Regards,
   

       
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