Using zip format for help pages, examples, etc.

Prof Brian D Ripley
Tue, 6 Apr 1999 08:02:45 +0100 (BST)

On 26 Mar 1999, Douglas Bates wrote:

> >>>>> "Jonathan" == Jonathan Rougier <> writes:
>   Jonathan> On Fri, 26 Mar 1999, Martyn Plummer wrote:
>   >> The problem isn't that the help files take up a lot of space, but
>   >> that certain file systems are extremely inefficient in the use of
>   >> that space.
>   Jonathan> This is probably an unrealistic suggestion, but if
>   Jonathan> compression is less of a problem than the number of files,
>   Jonathan> why not take the help files `onboard' by creating a new
>   Jonathan> class of objects with mode "help", which would be lists
>   Jonathan> with components much like the current .Rd files, and
>   Jonathan> attach them at the bottom of the search list.  Each
>   Jonathan> library would then require just a single file of help
>   Jonathan> objects.
> This is a reasonable suggestion but I think that the way that R
> handles its search lists would make this problematic.  At present
> objects in a library take up space in memory whether they are used or
> not.  Also, the search to resolve a name is a linear search over the
> available names.  Adding a whole lot more names for help objects would
> exacerbate both of those problems.  Then there is the name-space
> pollution problem.
> Approaches to all of these issues with names and objects are being
> discussed and will probably be implemented in later releases.  Right
> now I think the best approach to the problem of help files,
> etc. (other than waiting for certain commercial operating systems to
> catch up with concepts from the 1980's) is to use the zip format for
> the reasons that Brian Ripley indicated.

Doing this proved relatively easy and quite fast enough. It will appear
in the next Windows version (rw0640, I presume) that is due in a few days.
We just use unzip to extract a file and display it. (There is a DLL
version of unzip, but it seems unnecessary.)  Using zipped help is optional
by package, and where selected (when installing the package from source)
zips up the text, latex and example files. The space savings on a VFAT16
file system are considerable (about 20Mb on my system).

It is a little unfair to blame Windows: it has had more space-efficient
file systems (NTFS, FAT32) for some time. The problem is that not
everything else (notably Linux) could read/write these, and so they
were not the defaults.


Brian D. Ripley,        
Professor of Applied Statistics,
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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