[R] SAS and R

[Tim Churches]

Frank E Harrell Jr wrote:
> 
> It may be worth pointing out that the new read.ssd has to launch SAS 
> to convert to xport format.  The sas.get philosophy is that if you are 
> going to have to do that you might as well ask the sas session to dump 
> the data to ASCII files, with optional restriction to a subset of the
> variables.   That way you can fetch all the SAS attributes such as variable
> labels, data/time info, etc.  -Frank

SAS Version 8.2 provides an XML "engine" which allows you to write one
or an
ensemble of SAS datasets to an XML file (with a SAS-supplied DTD). The
usual
WHERE clause subsetting etc can be used with this engine. The XML
properly
represents date/time values and preserves the full precision of floats
(unlike
the SAS xport format which reduces the precision of numeric variables
from
56 bits to 53 bits). Best of all, the new SAS XML format preserves all
the
metadata such as dataset and variable labels, and even "formats"
(codebooks,
lookup tables): if a format is permanently associated with a variable,
the 
XML engine can be told to fetch the relevant format from an external
format
catalogue, convert it to an XML representation and enbed that in the
dataset
XML file. Hallelujah!

I haven't tried this yet, but it should be possible to use Duncan Temple
Lang's
XML package to parse the SAS dataset XML files and create a
fully-fledged
data frame complete with labelled factors etc.

Tim C
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