Re: [Gnuplot-info] Storing point from data file in variable

[Jeremy C. <jer...@gm...>]

On Thu, Jun 4, 2009 at 11:57 AM, Thomas Sefzick <t.s...@fz...>wrote:

>
> starting with gnuplot 4.3-cvs there are new operators
> '=' and ',' in expression syntax, that means, one can use
> them for the 'using' modifier inside a 'plot' command.
>
> defining labels must be done before plotting, but access
> to the data you don't have before plotting, so filling a variable
> with some value from the datafile can only be done
> when plotting (but then it's too late to define a label).
>
> one solution is to do a dummy plot by plot 'nothing to
> nowhere', by doing this you can set the variable.
> (plotting to nowhere can be done by specifying
> 'set out "/dev/null"' on unix systems, or, plotting
> nothing can be done by printing a table to
> the terminal window or text window)
> then you define the title, label, ....
> and afterwards you do the real plot.
>
> gnuplot> set table
> gnuplot> plot 'datafilename' us 0:($0==0?(x1=$3):$3)
> gnuplot> unset table
>
> for explanation of the syntax see
> gnuplot> help table
> gnuplot> help ternary
> gnuplot> help using
> gnuplot> help using pseudocolumns


Thank you for that great information.  I'll look up those help topics and if
I have any questions, I'll post them here.

Jeremy