[Gretl-devel] Re: Rdata import
On Mon, 16 Mar 2020, Sven Schreiber wrote:
Hi,
I stumbled again over the situation that gretl offers import support for
quite many third-party formats, but not explicitly for .Rdata files. I
have rechecked the mailing lists and AFAIU this was due to lack of
low-level standardization or unstable format specifications.
In practice I have been given a Rdata file which gretl apparently tries
to treat as a csv variant but cannot open. (I know I can go via native R
and that's what I will do, but that's not the point.)
So I was wondering if in the meantime things have stabilized enough;
perhaps this Library-of-Congress page is helpful? :
https://www.loc.gov/preservation/digital/formats/fdd/fdd000470.shtml
It's not so much a matter of stability or lack thereof, as the
polymorphism and opacity of Rdata. That Library of Congress page is
useful, but what I read there leads me to believe that an Rdata
importer would be a major project. Relevant snippets:
"The save function in R has options that result in significantly
different variants of the format."
"may include much more than the typical tabular data that might
be considered a 'dataset'"
"many RData files cannot be fully understood or used without access
to R extension packages"
"One expert... described the format as 'largely undocumented, and as
a result it is not much used as a way to exchange data with other
software.'"
"The RData format is not mentioned in the lists of formats accepted
by most statistical archives."
"The typical RData format is not transparent"
"The compilers of this resource are not aware of a convenient
mechanism for embedding structured metadata within an RData file."
[and so on]
I'd say, use gretl's "foreign" to open the .Rdata file in R, then
export to gretl what's actually wanted in gretl.
Allin