[NTG-context] graphics

Procházka Lukáš Ing. LPr at pontex.cz
Thu Dec 6 08:31:42 CET 2018


would it be possible to provide some samples finally?

That would be very handy especially for those who are used to create plots via "several clicks on Excel ribbon".

Personally, I am interested in 2D plots to be created loading (an) external data file(s) (text files formed into tables with some headers and comments marked by a letter in the beginning of the line), often altered by Lua somehow (e.g. trimming "bad" values).
I am used to use tickz/pgfplots for this purpose; use of pgfplots is (probably) very powerful but one has to study a lot of pages to create a simple plot followed by many try-and-see.
Also, support for showing extremal values (local extremes) in 2d plots is something handy.

"My" typical 2d plot looks:

30  |     24.1                         <- local extreme
     |     +
20  |  --- ---   15.6                 <- local extreme
     |/         \  +
10  |           -- ---
     10.     20.      30.      40.

Best regards,


On Tue, 04 Dec 2018 19:54:54 +0100, Alan Braslau <braslau.list at comcast.net> wrote:

> On Tue, 4 Dec 2018 18:03:14 +0100
> Hans Hagen <j.hagen at xs4all.nl> wrote:
>> Hi,
>> As most mechanism are reasonable okay now we can look into what
>> future versions of ConteXt should provide in terms of functionality.
>> The (luatex) engine is also more of less finished or at least stable
>> in terms of functionality.
>> One possible area of further development is graphics so I'd like to
>> know if there are (reasonable) demands for more graphics support
>> using metapost. Alan and I are on-and-off working on some extensions
>> and one of the things we discuss is visualization of data. The
>> question is of course what should be done in the lua/mp/tex
>> combination and what externally but the combination has some
>> advantages. There has been presentations and discussions at the last
>> meeting and graphics is always a nice topic, and also kind of
>> rewarding in terms of development.
>> Of course other demands can be formulated too, but these then need to
>> come with well defined descriptions (or mockup examples).
> Hans is alluding to work that we are doing to explore the possibilities
> of lua + MetaPost in the treatment and visualization of data,
> efficiently, with the possibility of handling large quantities of data.
> Lua does this particularly well.
> My first exercise has been a complete rewrite of the John Hobby graph
> macros. It was/is an exercise in recreating the functionality "from
> scratch", trying to use lua effectively when needed. The code and
> approach is entirely new. My use case was the analysis of a large set
> of data - entirely ridiculous for graphical display but containing
> "outliers" or instances that are significant, and it works! I am
> trying to generalize, and am doing this in my "free time".
> So the aim is two-fold:
> 1) to efficiently handle large datasets through the use of lua
> 2) to generalize the notion of user data space from the
> two-dimensional drawing space of MetaPost (and the represented page),
> and affine transformations of this 2D space to other coordinate
> systems and dimensions. We are not thinking about 3D rendering or
> raytracing, but rather simple projections and other transformations
> such as polar coordinates. (Of course, log scales, for example are a
> "simple" non-linear transformation.)
> I guess that Hans would like to expand the discussion to the future of
> graphics in general, inviting input from everybody.
> Alan

Ing. Lukáš Procházka | mailto:LPr at pontex.cz
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