[gnuplot] Choosing line type and color in Gnuplot 4.0

I have two pairs of datasets, which I need to plot using Gnuplot.

I want the first pair to be plotted in red, one solid and one dashed. The second pair, I want to plot in blue, one solid and one dashed.

I've experimented with set style line several times, but I cannot get this exact behaviour. My last attempt (attached) plots the first pair in red (solid) and the second pair in blue (dotted).

Any help will be greatly appreciated.

set style line 1 lt 1 lw 3 pt 3
set style line 2 lt 1 lw 3 pt 3
set style line 3 lt 3 lw 3 pt 3
set style line 4 lt 3 lw 3 pt 3
plot 'data1.dat' using 1:3 w l ls 1,\
     'data1.dat' using 1:4 w l ls 2,\
     'data2.dat' using 1:3 w l ls 3,\
     'data2.dat' using 1:4 w l ls 4

Here is the syntax:

  set terminal pdf {monochrome|color|colour}
                   {{no}enhanced}
                   {fname "<font>"} {fsize <fontsize>}
                   {font "<fontname>{,<fontsize>}"}
                   {linewidth <lw>} {rounded|butt}
                   {solid|dashed} {dl <dashlength>}}
                   {size <XX>{unit},<YY>{unit}}

and an example:

set terminal pdfcairo monochrome enhanced font "Times-New-Roman,12" dashed

You might want to look at the Pyxplot plotting package http://pyxplot.org.uk which has very similar syntax to gnuplot, but with the rough edges cleaned up. It handles colors and line styles quite neatly, and homogeneously between x11 and eps/pdf terminals.

The Pyxplot script for what you want to do above would be:

set style 1 lt 1 lw 3 color red
set style 2 lt 1 lw 3 color blue
set style 3 lt 2 lw 3 color red
set style 4 lt 2 lw 3 color blue
plot 'data1.dat' using 1:3 w l style 1,\
  'data1.dat' using 1:4 w l style 2,\
  'data2.dat' using 1:3 w l style 3,\
  'data2.dat' using 1:4 w l style 4`

You can also set the 'dashed' option when setting your terminal, for instance:

set term pdf dashed

I know the question is old but I found this very helpful http://www.gnuplot.info/demo_canvas/dashcolor.html . So you can choose linetype and linecolor separately but you have to precede everything by "set termoption dash" (worked for me in gnuplot 4.4).

I've ran into this topic, because i was struggling with dashed lines too (gnuplot 4.6 patchlevel 0)

If you use:

set termoption dashed

Your posted code will work accordingly.

Related question:
However, if I want to export a png with: set terminal png, this isn't working anymore. Anyone got a clue why?

Turns out, out, gnuplots png export library doesnt support this.
Possbile solutions:

• one can simply export to ps, then convert it with pstopng
• according to @christoph, if you use pngcairo as your terminal (set terminal pngcairo) it will work

You need to use linecolor instead of lc, like:

set style line 1 lt 1 lw 3 pt 3 linecolor rgb "red"

"help set style line" gives you more info.

Edit: Sorry, this won't work for you. I just remembered the line color thing is in 4.2. I ran into this problem in the past and my fix was to upgrade gnuplot.

You can control the color with set style line as well. "lt 3" will give you a dashed line while "lt 1" will give you a solid line. To add color, you can use "lc rgb 'color'". This should do what you need:

set style line 1 lt 1 lw 3 pt 3 lc rgb "red"
set style line 2 lt 3 lw 3 pt 3 lc rgb "red"
set style line 3 lt 1 lw 3 pt 3 lc rgb "blue"
set style line 4 lt 3 lw 3 pt 3 lc rgb "blue"