Multiply columns in a data frame by a vector

Question

What I want to do is multiply all the values in column 1 of a data.frame by the first element in a vector, then multiply all the values in column 2 by the 2nd element in the

Answer 1

Or simply diagonalize the vector, so that each row entry is multiplied by the corresponding element in v1:

c1 <- c(1,2,3)
c2 <- c(4,5,6)
c3 <- c(7,8,9)
d1 <- as.matrix(cbind(c1,c2,c3))
v1 <- c(1,2,3)

d1%*%diag(v1)

     [,1] [,2] [,3]
[1,]    1    8   21
[2,]    2   10   24
[3,]    3   12   27