In fact I have somethig like
   
      mat.dat<-matrix(rep(c(1,2,4,2,1,0,1,2),128*1024))
      write (mat.dat,"c:\\tmp\\mydat.txt")
   
        * remembering that I will run it about 500,000 times.
   
  The program that I will use to analyze (landscape metrics) my output files read text files ou generic binary files, where I can have each value separated by "space" (text format) or each value into a byte of 8 bits (for beneric binary files). A sample of generic binary is the "RAW" (row and columns) used for Adobe Photoshop. In fact, my matrix of data can be understood as a classifyed image.
   
  Kind regards,
   
  Miltinho
  

Duncan Murdoch <murdoch@stats.uwo.ca> escreveu:
  On 11/30/2006 6:55 AM, Milton Cezar Ribeiro wrote:
> Hi there,
> 
> I have a big amount of "lists" of data, each one with dimension 1024x1024. When I save it in an ASCII file (using "write" function) it take about 15 minutes. As I need run about 500,000 times this same routine, and I would like to do this save task in a fast way.

> In fact I will use these output files in another program that read ASCII or RAW/Generic Binary (8bits) formats. Each value from my lists ranges from 1 to 200 (integer values).

I think this depends on the details. Can you show us what str() gives 
for one of these lists? Can you tell us how flexible the other program 
is about the format of what it needs to see? "RAW/Generic Binary" 
sounds like a format for an image from a digital camera; there might be 
packages available in R that are specifically designed to write that 
format but I don't know them.

Duncan Murdoch


 		
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