[R] Hand-crafting an .RData file

[Gabor Grothendieck]

You can try read.csv.sql in the sqldf package. It reads a file into an
sqlite database which it creates for you using RSQLite/sqlite thus
effectively its done outside of R.  Then it extracts the portion you
specify using an sql statement and destroys the database.   Omit the
sql statement if you want the entire file.  Don't know if its faster
than read.table when used in that way but its only one line of code so
you could easily try it.  See example 13 on home page:
http://sqldf.googlecode.com

On Mon, Nov 9, 2009 at 12:27 AM, Adam D. I. Kramer <adik at ilovebacon.org> wrote:
> Hello,
>
>        I frequently have to export a large quantity of data from some
> source (for example, a database, or a hand-written perl script) and then
> read it into R.  This occasionally takes a lot of time; I'm usually using
> read.table("filename",comment.char="",quote="") to read the data once it is
> written to disk.
>
>        However, I *know* that the program that generates the data is more
> or less just calling printf in a for loop to create the csv or tab-delimited
> file, writing, then having R parse it, which is pretty inefficient. Instead,
> I am interested in figuring out how to write the data in .RData
> format so that I can load() it instead of read.table() it.
>
>        Trolling the internet, however, has not suggested anything about the
> specification for an .RData file. Could somebody link me to a specification
> or some information that would instruct me on how to construct a .RData
> file (either compressed or uncompressed)?
>
>        Also, I am open to other suggestions of how to get load()-like
> efficiency in some other way.
>
> Many thanks,
> Adam D. I. Kramer
>
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