32 - Colors in Gnuplot

Sometime one needs to use different colors to depict a figure. With the knowledge of the "Hex Code" of each color in Gnuplot, we can choose our favor color to plot.

To use "Hex Code"s we do as follow
pl 'FileName.dat' u 1:2 w lp lc rgb '#HexCode'

For example, the Hex Code for the blueviolet is 0000FF. The codes for each color can be found in
below figures. (From this Website)

23 - Plotting the last/first "N" lines of a data file within gnuplot

If we are interested in the last/first N lines of a data file and we would like to plot those, the needed
command in gnuplot is

> pl "< tail -N filename" u 1:2 w lp
which plots the last N lines,
or
> pl "< head -N filename" u 1:2 w lp
that plots the first N lines.

20 - Plotting a line paralle to y axis

If you want to plot your file like 'file.dat' then you want to have a parallel line to "y" axis, you can use:

> set arrow from 0, graph 0 to 0, graph 1 nohead
> plot 'file.dat'

In this case a line, x=0, will be plotted in your figure.
It is clear that for drwing, for example, x=1 line we need to use:

> set arrow from 1, graph 0 to 1, graph 1 nohead
> plot 'file.dat'

16 - plotting of subtraction of two columns in two different files in gnuplot

Suppose that we have two different files called File1.dat and File2.dat. The first file has 4 columns and the second file has 5 columns.
Our purpose is to plot the first column in the first file respect to difference of column 3 in the File1.dat and column 4 in the File2.dat. To do this we use the following command:

pl "< paste File1.dat File2.dat" u 1:($3-$8) w l

(with using this command, we assemble all columns in a same place. Therefor we have 4+4=8 columns where the first 4 columns belong to the first file and the rest ones belong to the second file.)

14 - general command for plotting in Gnuplot!

If you wan to plot a 2D (3D), here is the general command:

pl 'file.txt' u 1:2 w lp lt 2 lw 3 pt 4 ps 2 lc 3 t 'My title'

in this command:
pl = plot
u = using
w = with
lp = line point
lt = line type
lw = line width
pt = point type
ps = point size
lc = line color
t = title

12. Fitting data in a restricted range with Gnuplot

To to this, it is sufficient to use the following command (for example for a linear data fitting: y-ax+b)

> f(x)=a*x+b
> fit f(x) "< awk '{if($1>1 && $1<10) print $0}' data_file.txt" via a,b

11. X11 in gnuplot

If you want to see your plot in X11 window, type

set term x11

in the terminal.

9. How can we plot only a single point using Gnuplot?

To plot a single point with using Gnuplot, it is sufficient to use the following command:

plot "< echo 'x y' "

4. Gnuplot in cluster

If you want to use gnuplot in cluster, you have to connect to cluster with e.g.

ssh -Y kiani@ifflinux

after that, you can plot your data while you are in cluster.