尽管是64位版本，但无法在R中分配向量

Question

I am trying to do a dcast in R to generate a matrix as seen in another question I asked

However, I am getting an error:

Error: cannot allocate vector of size 2.8Gb.

My desktop has 8GB of RAM and I am running ubuntu 11.10 64-bit version. Am I perhaps using the wrong version of R? How would I know, is there a way to determine it while running R? I surely must have the necessary space to allocate this vector.

Answer 1

The error message means that R needs to allocate another 2.8Gb of memory to complete whatever operation you were trying to perform. It doesn't mean it needed to allocate 2.8Gb maximum. Run top in a shell whilst you run that R code and watch how R uses up memory until it hist a point where the extra 2.8Gb of address space is not available.

Do you have a large swap space on the box. I can easily see how what you are doing uses all 8Gb of RAM plus all your swap space and so there is no other place for R to get memory space from and thus throws the error.

Perhaps you could try doing the dcast in chunks, or try an alternative approach than using dcast. Post another Q if you want help with that.