[R] create a matrix with values from data.frame

[Nicolas Gutierrez]

Hello,

I'm trying to create a matrix (95x55) with data from a data.frame pop:

  xloc yloc      go  ind    Ene     totW
  1    23  20   516   1     0.02   20.21
  2    23  20  1143   1     0.02   20.21
  3    23  20   250   1     0.02   20.21
  4    22  15   251   1     0.02   18.69
  5    22  15   598   1     0.02   18.69
  6    21  19   250   1     0.02   20.21
  7    22  20   251   1     0.02   18.69
  8    22  20   598   1     0.02   18.69

where xloc is the x dimension,  yloc the y dimension, and totW the 
values for each cell (xloc,yloc) in my matrix (55x95):

I'm trying:

Bio=with(pop, (table(factor(totW, levels = 1:55), factor(totW, levels = 
1:95))))

But I don't get what I want. Hints? Thanks!

Nic