On Tue, Sep 21, 2010 at 9:50 AM, qcshare <qcsh...@gmail.com> wrote: > > Hello, everyone, > When I run R, I met: > "error:cannot allocate vector of size 400Mb", My data is large. > What should I do? > Thanks, everyone. >
How big is the RAM in your computer? There are a few things you can try: 1. Before running the analysis, shut down all other programs. Before you execute the analysis in R, issue garbage collection (call the function gc(), perhaps a few times). 2. If that doesn't help, try restarting your computer, not opening any applications except R, and follow point 1. 3. If 2. doesn't work, the next best step is to increase the amount of RAM, assuming your system and R can actually use it (e.g., 32 bit systems and R can typically only use 2-3 GB of memory - if you already have that much in your computer, adding more will not help). 4. If you can't get a bigger computer, try doing the analysis more cleverly. Often a large calculation can be split into smaller chunks with a small penalty in terms of performance or perhaps accuracy. If you can modify the code, try inserting garbage collection and/or modify the code to minimize the number of large objects held in memory. Knowing what is it you are trying to do would help. 5. If the analysis cannot be split into smaller chunks, the last resort is to only use it on a subset of data. You lose some accuracy/power/whatever, but it is better than having no results. 6. If you are a good Fortran or C programmer, and the analysis is relatively simple (or simple to code), the last last resort is to code the analysis in a compiled language where you may have better control over memory allocation and usage. You can write the analysis in say Fortran, compile it into a shared (dynamic-link) library, load the library into R and call the compiled code from R. However, all this is quite involved and should really be done as the last last resort if all else fails. Peter ______________________________________________ R-help@r-project.org 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.
