[R] bigmemory: Using backing file as alternate to write.big.matrix

[Shraddha Pai]

Hi,
Does the backing file of a big.matrix store the contents of entire matrix?
Or does it store the portion of it that is not stored in RAM? In other
words, can the backing file be treated as a file containing the matrix's
full data?

I have been writing my big.matrix objects to disk (write.big.matrix), and
other programs that want to access this matrix then just read it in
(read.big.matrix). A colleague pointed out that the explicit write
operation is unnecessary as the contents of the matrix are already in the
backing file. If the backing file is stored in the appropriate directory,
then future reads of the matrix can proceed directly from the matrix's
descriptor file (attach.big.matrix). Seems to make sense; no need to write
out in text format.

I just want to confirm from people more aware of the internals of the big
matrix that indeed the backingfile is a safe way to persistently store big
matrices. Looking at the documentation gave me pause because the backing
file is described as a "cache".

Thanks in advance,
Shraddha
-----
Shraddha Pai
Post-doctoral fellow
Krembil Family Epigenetic Research Laboratory (Lab head: Dr. Art Petronis)
Centre for Addiction and Mental Health, Toronto



 

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