Use gzcon() to make a compressed connection and any
function that write to a connection will write compressed
data. E.g.,
> con <- gzcon(file("tempfile.junk", "wb"))
> x <- as.integer(rep(c(-127, 1, 127), c(3,2,1)))
> writeBin(x, con, size=1)
> close(con)
> q("no")
bill:158% zcat tempfile.junk | od --format d1
0000000 -127 -127 -127 1 1 127
0000006
(In this tiny example the gzip'ed file is bigger than the
equivalent one, but it is gzip'ed.)
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf Of Mike Miller
> Sent: Thursday, September 08, 2011 8:14 AM
> To: Duncan Murdoch
> Cc: R-Help List
> Subject: Re: [R] storage and single-precision
>
> On Thu, 8 Sep 2011, Duncan Murdoch wrote:
>
> > On 11-09-07 6:25 PM, Mike Miller wrote:
> >
> >> I'm getting the impression from on-line docs that R cannot work with
> >> single-precision floating-point numbers, but that it has a pseudo-mode
> >> for single precision for communication with external programs.
> >>
> >> I don't mind that R is using doubles internally, but what about
> >> storage? If all I need to store is single-precision (32-bit), can I do
> >> that? When it is read back into R it can be converted from single to
> >> double (back to 64-bit).
> >>
> >> Furthermore, the data are numbers from 0.000 to 2.000 with no missing
> >> values that could be stored just as accurately as unsigned 16-bit
> >> integers from 0 to 2000. That would be the best plan for me.
> >
> >
> > writeBin is quite flexible in converting between formats if you just
> > want to store them on disk. To use nonstandard formats in memory will
> > require external support; it's not easy.
>
>
> Thanks. I can see now that writeBin will store unsigned 16-bit integers,
> which is what I want. There is one other issue -- with save() I'm allowed
> to use compression (e.g., gzip), but there doesn't seem to be a
> compression option in writeBin. Is there a way to get the best of both
> worlds? The data are highly nonrandom and at most 11 bits will be used
> per integer, so the compression ratio should be pretty good, if I can have
> one.
>
> Mike
>
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