Perhaps use the digest package? Isn't "R the R packages?"
> On May 1, 2020, at 2:00 PM, Dénes Tóth <toth.de...@kogentum.hu> wrote:
>
>
> AFAIK there is no hashing utility in base R which can create hash digests of
> arbitrary R objects. However, as also described by Henrik Bengtsson in [1],
> we have tools::md5sum() which calculates MD5 hashes of files. Calculating
> hashes of in-memory objects is a very common task in several areas, as
> demonstrated by the popularity of the 'digest' package (~850.000
> downloads/month).
>
> Upon the inspection of the relevant files in the R-source (e.g., [2] and
> [3]), it seems all building blocks have already been implemented so that
> hashing should not be restricted to files. I would like to ask:
>
> 1) Why is md5_buffer unused?:
> In src/library/tools/src/md5.c [see 2], md5_buffer is implemented which seems
> to be the counterpart of md5_stream for non-file inputs:
>
> ---
> #ifdef UNUSED
> /* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
> result is always in little endian byte order, so that a byte-wise
> output yields to the wanted ASCII representation of the message
> digest. */
> static void *
> md5_buffer (const char *buffer, size_t len, void *resblock)
> {
> struct md5_ctx ctx;
>
> /* Initialize the computation context. */
> md5_init_ctx (&ctx);
>
> /* Process whole buffer but last len % 64 bytes. */
> md5_process_bytes (buffer, len, &ctx);
>
> /* Put result in desired memory area. */
> return md5_finish_ctx (&ctx, resblock);
> }
> #endif
> ---
>
> 2) How can the R-community help so that this feature becomes available in
> package 'tools'?
>
> Suggestions:
> As a first step, it would be great if tools::md5sum would support connections
> (credit goes to Henrik for the idea). E.g., instead of the signature
> tools::md5sum(files), we could have tools::md5sum(files, conn = NULL), which
> would allow:
>
> x <- runif(10)
> tools::md5sum(conn = rawConnection(serialize(x, NULL)))
>
> To avoid the inconsistency between 'files' (which computes the hash digests
> in a vectorized manner, that is, one for each file) and 'conn' (which expects
> a single connection), and to make it easier to extend the hashing for other
> algorithms without changing the main R interface, a more involved solution
> would be to introduce tools::hash and tools::hashes, in a similar vein to
> digest::digest and digest::getVDigest.
>
> Regards,
> Denes
>
>
> [1]: https://github.com/HenrikBengtsson/Wishlist-for-R/issues/21
> [2]:
> https://github.com/wch/r-source/blob/5a156a0865362bb8381dcd69ac335f5174a4f60c/src/library/tools/src/md5.c#L172
> [3]:
> https://github.com/wch/r-source/blob/5a156a0865362bb8381dcd69ac335f5174a4f60c/src/library/tools/src/Rmd5.c#L27
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
---------------
John Mount
http://www.win-vector.com/ <http://www.win-vector.com/>
Our book: Practical Data Science with R
http://practicaldatascience.com <http://practicaldatascience.com/>
[[alternative HTML version deleted]]
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
