I have to plot a data file which is in a triangular domain. To make it clearer, my data file possess 3 value, two frequencies f1 and f2 with a sum lower or equal to 100 (i.e. f1 + f2 <= 100) and a metric m. My data file is structured as follow:
f1 f2 m
0 0 x1
...
0 100 xn
5 0 xn+1
...
100 0 xm
...
100 100 xm+n
with a blank line each time f1 changes. I plot a view map with a colorbox representing the metric m. Here is a minimal example:
set view map scale 1
set style data pm3d
set pm3d ftriangles
set xrange [0:100]
set yrange [0:100]
splot 'datafile.dat' u 1:2:3
Given the following result
To plot the contour plot of this map, I use the following script:
set view map scale 1
unset surface
set style data lines
set dgrid3d
set contour both
set xrange [0:100]
set yrange [0:100]
set cntrparam levels auto 23
splot 'datafile.dat' u 1:2:3
I got the following image:
As we can see, a part of the contour plot is above the line f(x)=100-x which shouldn't happen due to the constraint f1 + f2 <= 100.
So, here is my question: is there a way to hide the lines' parts which are above the line f(x)=100-x ?