On 31/08/2012 15:41, Duncan Murdoch wrote:
On 31/08/2012 9:47 AM, Damien Georges wrote:
Hi all,
I'm working with some huge array in R and I need to load several ones to
apply some functions that requires to have all my arrays values for each
cell...
To make it possible, I would like to load only a part (for example 100
cells) of all my arrays, apply my function, delete all cells loaded,
loaded following cells and so on.
Is it possible to unserialize (or load) only a defined part of an R
array ?
Do you know some tools that might help me?
I don't know of any tools to do that, but there are tools to maintain
large objects in files, and load only parts of them at a time, e.g. the
ff package. Or you could simply use readBin and writeBin to do the same
yourself.
Serialization is essentially serial, so you can only read the serialized
format from the beginning. So too are the compression algorithms used
by default.
Finally, I did lot of research to find the way array (and all other R
object) are serialized into binary object, but I found nothing
explaining really algorithms involved. If someone has some information
on this topic, I'm interesting in.
You can read the source for this; it is in src/main/serialize.c.
And there is an extensive commentary in the 'R Internals' manual.
--
Brian D. Ripley, rip...@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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