On 11/30/2006 8:19 AM, Milton Cezar Ribeiro wrote: > 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.
The RAW format is probably the fastest to write. Use writeBin(as.integer(mat.dat), "c:\\tmp\\mydat.raw", size=1). This writes in column-major order (i.e. column 1, then column 2, etc.). You need to transpose the matrix before writing if you want row-major order. Duncan Murdoch > > Kind regards, > > Miltinho > > > Duncan Murdoch <[EMAIL PROTECTED]> 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 > > > > --------------------------------- > Novidade no Yahoo! Mail: receba alertas de novas mensagens no seu celular. > Registre seu aparelho agora! ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
