[NTG-context] Lua and module gnuplot: Manipulate Gnuplot script with Lua

12 Dec 2011

      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

        \startGNUPLOTscript[nolua]
           plot 1.2 * x + 3
        \stopGNUPLOTscript

        \starttext
        \useGNUPLOTgraphic[lua]

        Above should be a plot.

        \useGNUPLOTgraphic[nolua]

        \blank
        \CONTEXT\ \contextmark\ \contextversion
        \stoptext

But only the second plot done and for the first the following error is
shown.

        mtxrun          |
        mtxrun          | executing: gnuplot gnup-gnuplot-1.plt
        mtxrun          |
        mtxrun          |
           plot \ctxlua{context(1.2 * x + 3)}
                ^
        "gnup-gnuplot-1.tmp", line 1: invalid character \

Is there a way to manipulate gnuplot scripts with Lua?

Thanks,

Paul

[NTG-context] Lua and module gnuplot: Manipulate Gnuplot script with Lua

Paul Menzel