[R] how to superimpose 2 matrices of different sizes

[Nicolas Gutierrez]

Hi All,

I’m trying to superimpose (or "add")  two matrices:

1. resulting from a table function with frequencies:

 > U=table(pop$xloc, pop$yloc))

       14 15 16 17 18 19 20 21 22
   5   0  0  0  0  0  0  0  0  0
   7   0  0  0  0  0  0  0  0  0
   8   0  0  0  0  0  0  0  0  0
   9   0  0  0  0  0  0  9  0  5
   10  0  0  0  0  0  0  0  0  0
   11  0  0  0  0  0  0  0  0  0

2. The second created to match my spatial grid (20x25):

 > Uempty=matrix(data = 0, nrow = 20, ncol = 25)

I want to place each element of U (e.g. U[22,9]=5) in the corresponding 
cell of Uempty and end up with this final matrix like this:

       1  2  3 ...  22 23 24 25
   5   0  0  0  ...  0  0  0  0
   :   :  :  :  ...  :  :  :  :
   7   0  0  0  ...  0  0  0  0
   8   0  0  0  ...  0  0  0  0
   9   0  0  0  ...  5  0  0  0
   :   :  :  :  ...  :  :  :  :
   20  0  0  0  ...  0  0  0  0

Any ideas?

Thanks!!!

Nico