[R] memory blues

[Prof Brian Ripley]

On Thu, 10 May 2001, Bernie McConnell wrote:

> G'Day again,
>
> I am attempting to read a large MSAccess file into R,  but get memory
> problems.  With the first 100 rows of the table ("Macca99") things, as
> shown below, are fine and the resulting object is 33,780 bytes.  But when I
> read the entire table ("MaccaDiv99") which is 218,000 rows  R falls over
> with the message:
>
> Rgui.exe - Application error
> The instruction at "0x025d0458" referenced memory at "0x0000003a".
> The memory could not be "read"
>
> My arithmetic suggests that the resulting object should have been about
>  33,708 * 218,000 / 100 = c. 74 Mbytes.  I'm running Win NT with 256 Mbyte
> memory so I was expecting to be able to read in the entire table.  Or am I
> being hopelessly naive?

Probably.  R certainly requires several times the size of the final object
for these operations. Try reading it in pieces, or set "as" to read it as
a matrix and then convert.


-- 
Brian D. Ripley,                  ripley at 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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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