[R] Reading xpt files into R

[David Winsemius]

> On Apr 13, 2018, at 10:01 AM, WRAY NICHOLAS via R-help <r-help using r-project.org> wrote:
> 
> Hello R folk
> 
> I have an xpt file which I have been trying to open into R in R studio
> 
> On the net I found guidance which says that I need packages Hmisc and SASxport which I have successfully loaded.
> 
> I had also found some code which says that this would allow me to read the xpt file into R:
> 
> library(SASxport)
> data(Alfalfa)
> lookup.xport("test.xpt")
> Alfalfa<-read.xport("test.xpt")
> 
> I have set the directory correctly as far as I am aware, but when I tried to run this code I got the following error messages:
> 
>> lookup.xport("test.xpt")
> Error in lookup.xport.inner(file) : file not in SAS transfer format
>> Alfalfa<-read.xport("test.xpt")
> Error in read.xport("test.xpt") : 
> The specified file does not start with a SAS xport file header!
> 
> I neither know what the file being not in SAS transfer format means, nor what not starting with an SAS xport file header means either...

The "export" or "transfer format from SA is supposed to make reading data less difficult and standardized. This is what a header from the version used by the NHANES releases (that's all one line):

HEADER RECORD*******LIBRARY HEADER RECORD!!!!!!!000000000000000000000000000000  SAS     SAS     SASLIB  9.2     XP_PRO                          16SEP09:09:39:2516SEP09:09:39:25                                                                HEADER RECORD*******MEMBER  HEADER RECORD!!!!!!!000000000000000001600000000140  HEADER RECORD*******DSCRPTR HEADER RECORD!!!!!!!000000000000000000000000000000  SAS     DEMO    SASDATA 9.2     XP_PRO                          16SEP09:09:39:2516SEP09:09:39:25                                                                HEADER RECORD*******NAMESTR HEADER RECORD!!!!!!!000000014400000000000000000000   
    
SEQN    Respondent sequence number                                      

You can look at the file with a text editor.

There is a read.xport function in the foreign package and I think most people would have chosen that one as a first attemp. It's part of the standard R distribution. It refers you to https://support.sas.com/techsup/technote/ts140.pdf for details on the format.

-- 
David.
> If anyone can explain how I can read this xpt file into R I'd be v grateful
> 
> Thanks Nick Wray
> 
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> 
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David Winsemius
Alameda, CA, USA

'Any technology distinguishable from magic is insufficiently advanced.'   -Gehm's Corollary to Clarke's Third Law