On Mon, Dec 12, 2011 at 22:39, Paul Menzel wrote: > Dear ConTeXt folks, > > > I have two coefficients saved in a text file > > -0.157737135681261 > -0.211443105668896 > > and I want to use them to plot a line with gnuplot. > > Having several of those files I want to use Lua to create the formula > for the line for me. > > I have not yet figured out how to read values from a file in Lua and > just tried to print a constant to the gnuplot command. > > I tried the following. > > \usemodule[gnuplot] > > \startGNUPLOTscript[lua] > plot \ctxlua{context(1.2 * x + 3)} > \stopGNUPLOTscript
This won't work. The reason is that contents between \startGNUPLOTscript and \stopGNUPLOTscript are not parsed by ConTeXt on purpose. It was very very very painful if not impossible to get it right with parsing. I often do things like \def\E#1{$10^{#1}$} \startGNUPLOTscript[name] set logscale y set format y "\\E{%T}" plot sin(x) t '$\sin(x) [\E{3}]$' # usually something else with logscale, but just to show the point \stopGNUPLOTscript and if ConTeXt starts parsing this it becomes a pure nightmare. Realize that it can easily happen that ConTeXt then writes out set logscale y set format y "<some junk leftovers from \\> E<ungrouped { since % starts comment> plot sin(x) t '\math{\mathrm{sin}(x) [{10^{3}}]}' <arbitrary junk from expansion ...> However, \startGNUPLOTinclusions is parsed and you could in theory misuse that, but it would be very bad coding practice. It would be a lot better to come up with some proposal how to change the interface to enable what you want to do. (To be honest, it is still on my todo list to migrate to Aditya's filter module in the background, but I don't find the courage to start since I have no idea how many bugs will creep in.) But a serious question: what *exactly* do you want to do with lua that you are unable to do with some (even though ugly) gnuplot trickery? Gnuplot does have some basic programmable capabilities. I can imagine that you should be able to do something like: # params.dat a=-0.157737135681261 b=-0.211443105668896 \startGNUPLOTinclusions f(x,a,b)=a*x+b \stopGNUPLOTinclusions \startGNUPLOTscript[name] load 'params.dat' plot f(x,a,b) \stopGNUPLOTscript And if needed you can create params.dat on the fly (but I believe that the same should be doable even if you start with just pure data values and do some dirty tricks in gnuplot). Yet another trick could be to create a text file on the fly with lua (if you really really really need that) and then your script only says something like. # bla.plt created on the fly with lua scripts plot 1.2 * x + 3 \startGNUPLOTscript[bla] load 'bla.plt' \stopGNUPLOTscript I leave creating a suitable 'bla.plt' with lua to others ... Mojca ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________