Is it possible to set the “linetype” in gnuplot while using “linecolor variable”?

4
votes

I have a tab-separated data file containing a number of (double-blank-line-separated) datasets and I want to plot a line for each of them. I want to be able to set the linetype (by this I'm referring to solid/dashed/dotted). I want each line to be a different color.

I can plot them all different colors using this:

plot 'example.dat' using 1:2:(column(-2)) with lines linecolor variable

And I can set the linetype but plot them all the same color using this:

plot 'example.dat' using 1:2:(column(-2)) with lines linetype 5

But when I combine them, the linetype is not what I set it to (in this case I just get a solid line).

plot 'example.dat' using 1:2:(column(-2)) with lines \
  linetype 5 linecolor variable

Is there a way to achieve this?

I'm using gnuplot 4.6, tried with the x11 and postscript terminals.

1
gnuplot

1 Answers

3
votes

This looks like a bug to me. Unfortunately, I don't think too many gnuplot devs hang out on StackOverflow, so we might not ever find out. (I would encourage you to submit a bug report though and keep me updated on any progress that might be made)...

If you're really using column(-2) to pick out the colors, the problem becomes a lot easier and you should be able to do that using plot iteration (as long as you know an upper limit on the number of datasets).

NDSET=3 #This will issue a warning if NDSET is too big, but will still work.
plot for [IDX=0:NDSET] 'example.dat' index IDX using 1:2 with lines linetype 5 linecolor IDX+1

The indexing starts from 0 and corresponds to column(-2). Linecolor 0 isn't defined (I don't know why gnuplot uses two different conventions here -- I suppose because in theory the colors corresponding to any particular linestyle are terminal dependent, so it doesn't really matter too much anyway...)