[R] Memory/data -last time I promise

[Mark Myatt]

Michael Taylor wrote:

> 2) Ultimately I would like to replace Stata with R, but the Stata
>datasets I frequently use are in the 100s of megs, which work fine on
>this machine. Is R capable of this?

Brian Ripley replied:

>Probably not.  R does require objects to be stored in memory.

I think Stata also required that objects reside in memory. It is quite a
time since I have used Stata (I have v4 on my shelves) but I remember
that it was no good for cancer registry work (big datasets) as it needed
everything to be in memory and we only have 16MB Win 3.11 machines at
the time.

There is a storage difference between R and Stata. Stata has several
number types (byte, short integer, long integer, single precision float,
double precision float) whereas R has only the integer (equivalent to
long integers, I think) and real/numeric/double which are all double
precision floats. This means that R will often require more memory to
store objects than Stata. Your "14 MB" file could easily swell to many
times that size if Stata 'byte' types are being stored as double
precision numbers.

I am not aware if there are plans to add different storage modes to R
but doing so might be useful particularly with large datasets.

Just my tuppence.

Mark


--
Mark Myatt


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