How to multiple the vector and variables from dataframe

Hi Neal,

Notice that c(2, 3) gets replicated into c(2, 3, 2, 3, 2, 3) and then
multiplied by column. This is not the same as multiplying each column by
the respective element in vector c(2, 3).

Andrius


2012/12/30 Neal H. Walfield <neal at walfield.org>

At Sun, 30 Dec 2012 18:26:45 +0800 (CST),
meng wrote:

hi all:
Here's a dataframe(dat) and a vector(z):

dat:
x1     x2    x3
0.2   1.2   2.5
0.5   2      5
0.8   3      6.2

z

[1]  10 100 100

I wanna do the following:
10*x1,100*x2,1000*x3

My solution is using the loop for z and dat(since the length of z is the

same as ncol  of dat),which is tedious.

I wanna an efficient solution to do it .

You could convert the data frame to a matrix:

dat=data.frame(x1=1:3, x2=11:13)
dat

  x1 x2
1  1 11
2  2 12
3  3 13

as.matrix(dat) * c(3, 2)

     x1 x2
[1,]  3 22
[2,]  4 36
[3,]  9 26

Neal