Question

I have this R code:

> coef
[1] 1.5 2.4 3.9 4.4
> y
     [,1] [,2] [,3] [,4]
[1,]    1    2   12   45
[2,]    5    6    7    8
[3,]    9   10    2   12
[4,]   13   14   15   45
[5,]   17   18   39    7

I have to multiply each value of the column with the respective coef. The result should be:

First column:
1*1.5 
5*1.5 
9*1.5 
13*1.5 
17*1.5

Second column: 
2*2.4 
6*2.4 
10*2.4 
14*2.4 
18*2.4

Third column: 
12*3.9 
7*3.9 
2*3.9 
15*3.9 
39*3.9

Fourth column: 
45*4.4
8*4.4
12*4.4 
45*4.4 
7*4.4

All the column’s values moltiplied by the same coefficient at the same index in the vector.

How can I do this calculation?

The solution could be:

> y[,1] <- y[,1] * coef[1]
> y[,2] <- y[,2] * coef[2]
> y[,3] <- y[,3] * coef[3]
> y[,4] <- y[,4] * coef[4]

But doesn’t seem too optimized! Something better?

Thank you!

Answer 1

This will give you what you want:

t( t(y) * coef  )