Bug#227645: Document how to plot compressed file

[Witold Baryluk]

Package: gnuplot
Version: 5.2.5+dfsg1-1
Followup-For: Bug #227645

It isn't really a defect in gnuplot, because it can be done and is documented.

plot "< xyz" ...

(piped-data) is extremally powerful, often used with sed, grep, awk, cat/zcat or other tools
to do arbitrary preprocessing that can't be done with input spec or 'using'.

I agree, that documentation could show more examples, because
it is so powerful and underutilized.

Automatic heuristic to discover some magic headers for gz/bz4/xz/lz4/lzo
plus heuristic to look at the extension of the filename, could be useful
useful tho, especially for new users, or:

plot "file.gz" decompress=auto ...

to not even use heuristic. The problem with heuristic would be that it
will not work for tar.gz files, or zip files, as these can contain more than
one file, but initial support could simply treat them as separate datasets
or just use first one and error out if there is more than one.

Similar to plot "xyz.png" binary filetype=png can do read arrays.
In fact for some simple formats simply plot "..." binary filetype=gzip could
do the trick.

In the mean time it would be nice to document this upstream as one of example.


Best regards,
Witold



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ii  gnuplot-x11 [gnuplot-nox]  5.2.5+dfsg1-1

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Versions of packages gnuplot suggests:
pn  gnuplot-doc  <none>

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