[R] Fwd: Re: Reading xpt files into R

[William Dunlap]

 > When I look at the SASxport::read.xport function code, it is in fact,
_not_ the
> same function. But it does have the R statement about what it thinks
> qualifies as a SAS xprot file:
>
> xport.file.header <- "HEADER RECORD*******LIBRARY HEADER RECORD!!!!!!!000000000000000000000000000000
"
>
> It checks to see whether the file starts with that string.

Version 8 SAS xport files have the header
  HEADER RECORD*******LIBV8 HEADER RECORD!!!!!!!000000000000000000000
000000000
It is easy to check for that in your text editor or in R.

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Sat, Apr 14, 2018 at 1:30 PM, David Winsemius <dwinsemius using comcast.net>
wrote:

>
> > On Apr 14, 2018, at 12:18 PM, WRAY NICHOLAS via R-help <
> r-help using r-project.org> wrote:
> >
> >
> > -------- Original Message ----------
> > From: WRAY NICHOLAS <nicholas.wray using ntlworld.com>
> > To: peter dalgaard <pdalgd using gmail.com>
> > Date: 14 April 2018 at 20:18
> > Subject: Re: [R] Reading xpt files into R
> >
> >
> > Well yesterday I'd downloaded the "foreign" package and tried to open
> the xpt file using that:
> >
> > library(foreign)
> > read.xport("test.xpt")
> >
> > I got the following error and warning messages:
> >
> >> read.xport("test.xpt")
> > Error in read.xport("test.xpt") :
> > The specified file does not start with a SAS xport file header!
> > In addition: Warning message:
> > In readBin(file, what = character(0), n = 1, size =
> nchar(xport.file.header,  :
> > null terminator not found: breaking string at 10000 bytes
> >
> > I can open the xpt using wordpad and there is a header but it seems to
> be just text.  I really don't know what constitutes an "
> > SAS xport file header"
>
> I'm not sure why Peter deleted my copy of a sample of a SAS xport header
> that I took from an NHANES data distribution. He seemed to think I was
> confused about the function you had been using. The reason I mentioned that
> `read.xport` was from the 'foreign' package is that one generally loads
> that package to make the function available, while it appears you were
> using a different package, SASxport, and I didn't know whether that package
> had a function which had the same name as the one from pkg-foreign, and if
> it did whether it might depend on the read.xport function in foreign. You
> should not need to download the 'foreign' package, since it ships with
> every distribution of R. These are the arguments accepted by that function:
>
> SASxport::read.xport
> function (file, force.integer = TRUE, formats = NULL, name.chars = NULL,
>     names.tolower = FALSE, keep = NULL, drop = NULL, as.is = 0.95,
>     verbose = FALSE, as.list = FALSE, include.formats = FALSE)
>
>
>  When I look at the SASxport::read.xport function code, it is in fact,
> _not_ the same function. But it does have the R statement about what it
> thinks qualifies as a SAS xprot file:
>
> xport.file.header <- "HEADER RECORD*******LIBRARY HEADER RECORD!!!!!!!000000000000000000000000000000
> "
>
> It checks to see whether the file starts with that string.
>
> This is what appeared in my first message:
>
> >
> > 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
>
> So the header is text, but it is text with a particular structure. If your
> file doesn't have that structure, then it's not a SAS xport file. The .xpt
> extension is also used for Mozilla Firefox plugins.
>
>
> >
> > Nick
> >
> >
> >
> > On 14 April 2018 at 10:32 peter dalgaard <pdalgd using gmail.com> wrote:
> >
> > That's what he tried,
>
> Actually not, Peter. Wray was using a function of the same name, but not
> from pkg-foreign. Perhaps he was following the tutorial at:
>
> http://www.phusewiki.org/wiki/index.php?title=Open_XPT_File_with_R
>
>
> > but the bottom line is that just because something is called foo.xpt
> there is no guarantee that it actually is a SAS XPORT file. Firefox plugins
> use the same extension but it could really be anything - naming conventions
> are just that: conventions.
> >
> > So dig deeper and find out what the file really is (or was supposed to
> be).
>
> Peter and I agree agree on that advice.
>
> >
> > -pd
> >
> >>
> >>            On 14 Apr 2018, at 00:18 , David Winsemius <
> dwinsemius using comcast.net> wrote:
> >>
> >>            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 Winsemius
> Alameda, CA, USA
>
> 'Any technology distinguishable from magic is insufficiently advanced.'
>  -Gehm's Corollary to Clarke's Third Law
>
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