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A Simple Guide to  GNU Plot >

Plotting:

Start GNU Plot just by typing "gnuplot":
 

benny:/scratch/archive/acz/www:2466> gnuplot         G N U P L O T         Unix version 3.7                < more stuff here > Terminal type set to 'x11' gnuplot>

As you may have noticed the terminal is set to x11, what means that all the drawing commands will output the results on a window. Please remember this as by changing the terminal type, later, you can output your plots in different formats.

Let's start with the simple plot:
 

gnuplot> plot "carrots.dat"

Now you should see a new window with the points for the dept of EEE. This is because, by default plot command uses the first two columns of your data file.

With this command:
 

gnuplot> plot "carrots.dat" using 1:3

you can display the data for the other department. But you want them together, connected with lines:
 

gnuplot> plot "carrots.dat" using 1:2 with linespoints, "carrots.dat" using 1:3 with linespoints

Almost perfect. But still you do not like "carrots.dat" on your diagram and you would prefer more meaningfull names:
 

gnuplot> plot "carrots.dat" using 1:2 t "Dept of EEE" with linespoints, "carrots.dat" using 1:3 t "Dept of CS" with linespoints

Let's assume that you also want to specify the year range from 1985 till 2005, and fix the carrot consumption range:
 

gnuplot> plot [1985:2005] "carrots.dat" using 1:2 t "Dept of EEE" with linespoints, "carrots.dat" using 1:3 t "Dept of CS" with linespoints gnuplot> plot [1985:2005] [0:200] "carrots.dat" using 1:2 t "Dept of EEE" with linespoints, "carrots.dat" using 1:3 t "Dept of CS" with linespoints

Let's assume that you also prefer to have the legend below the diagram:
 

gnuplot> set key below

(you have to redraw it to see the difference - use up and down arrows to access previous/next commands)

Finally you want to add the title and the axle labels:
 

gnuplot> set title "The comparison of the consumption of carrots\nby the departments of EEE and CS in years 1990-2000" gnuplot> set xlabel "Year" gnuplot> set ylabel "Consumption\nof carrots [kg]"

Please note that I used \n to force the new line characters.
(again you have to redraw to see any changes)

OK, let's assume that now you are happy about your plot. It should look like this:

Now you want to obtain a high quality file which you can insert into your document.
There are many formats supported but I will describe only how to generate files in Encapsulated PostScript file format (EPS, .eps).

As I mentioned before you can do this by changing the terminal:
 

gnuplot> set terminal postscript eps color

Also you can specify the name of the output file:
 

gnuplot> set output "carrots.eps"

And plot again, that is type plot <whatever you want> or use arrows to find the previous plot line and execute it. Nothing should change on your plot window but a new file "carrots.eps" should appear in your directory.
If you plot again the result will again be written to the same file, hence remember to change the output variable for the next plot.

If you want again see your plots in the plot window simply change the terminal to x11:
 

set terminal x11

Now, from another terminal window (so you do not have to exit GNU plot) you can try to view the new file with ghostview:
 

benny:/scratch/archive/acz/www:2468> ghostview carrots.eps

Does it look fine ? Hopefully it does.

If you do not need GNU plot anymore:
 

gnuplot> quit

Now you can insert your images to your LaTeX documents or M$ Word or M$ PowerPoint or Star Office. If you use UNIX-like systems (Solaris, Linux, etc.) you should have no problems with handling PostScript or Encapsulated PostScript files. Unfortunately M$ software has very poor support for PostScript. If you have a PostScript printer you should have no problems with printing from M$ software. If not, you may have to print from the ghostview or Acrobat reader.

If you really cannot print your final document in M$ environment, install any PostScript printer driver and print to a file. Now convert that file into PDF format with e.g. ghostview (choose the device pdfwrite) or Acrobat Distiller. Now you should have a PDF version of your document (e.g. carrot_report2005.pdf) which you can view or print from an Acrobat Reader on any printer or e-mail to someone.
 

Usefull Hints:

Use a text editor (e.g. nedit) as a scratch pad. Store there all the commands you need to produce plots you want. You can select a few lines with gnuplot commands and paste them in gnuplot window, e.g. by pressing the middle mouse button.

For the example above you can have a text file with:
 

set terminal postscript eps color set output "carrots.eps" set key below set title "The comparison of the consumption of carrots\nby the departments of EEE and CS in years 1990-2000" set xlabel "Year" set ylabel "Consumption\nof carrots [kg]" plot [1985:2005] [0:200] "carrots.dat" using 1:2 t "Dept of EEE" with linespoints, "carrots.dat" using 1:3 t "Dept of CS" with linespoints

and you select all these lines (even now from your browser window) and paste in gnuplot window.

If you, for example, want to use the carrot data from this page you can, in a terminal window, type:
 

cat > carrot.dat

select the "carrot.dat" data lines in your web browser, press the middle mouse button inside the terminal window with cat command waiting for any data. When the data appears simply press Control + D (not C nor Z!) to close the file.
 

Last word:

On this page I have described only a tiny subset of GNU plot commands. If you type help or help <topic> (e.g. help plotting) you will get much more information.

That's it.