Book Image

gnuplot Cookbook

By : Lee Phillips
Book Image

gnuplot Cookbook

By: Lee Phillips

Overview of this book

gnuplot is the world's finest technical plotting software, used by scientists, engineers, and others for many years. It is in constant development and runs on practically every operating system, and can produce output in almost any format. The quality of its 3d plots is unmatched and its ability to be incorporated into computer programs and document preparation systems is excellent. gnuplot Cookbook ñ it will help you master gnuplot. Start using gnuplot immediately to solve your problems in data analysis and presentation. Quickly find a visual example of the graph you want to make and see a complete, working script for producing it. Learn how to use the new features in gnuplot 4.4. Find clearly explained, working examples of using gnuplot with LaTeX and with your own computer programming language. You will master all the ins and outs of gnuplot through gnuplot Cookbook. You will learn to plot basic 2d to complex 3d plots, annotate from simple labels to equations, integrate from simple scripts to full documents and computer progams. You will be taught to annotate graphs with equations and symbols that match the style of the rest of your text, thus creating a seamless, professional document. You will be guided to create a web page with an interactive graph, and add graphical output to your simulation or numerical analysis program. Start using all of gnuplot's simple to complex features to suit your needs, without studying its 200 page manual through this Cookbook.
Table of Contents (18 chapters)
gnuplot Cookbook
About the Author
About the Reviewers
Finding Help and Information

Making a labeled contour plot

We got an introduction to contour plots in Chapter 8, The Third Dimension, where we saw that the contours can be drawn in a sequence of dash-dot styles; the contour values can then be identified by referring to the legend that gnuplot constructs for us automatically.

There is another style of contour plot that incorporates numerical labels directly on the contours. gnuplot does not support this style directly, but can be tricked into compliance, as shown in the following figure:

How to do it…

Type the following script:

unset key
unset surf
set view map
set contour base
unset clabel
set xrange [0:5]
set yrange [0:5]
set style fill solid
set for [n = 1:4] cntrparam levels discrete n**2
set for [n = 1:4] object n circle at n,n size 0.2 front fillcolor rgb '#ffffff' lw 0
set for [n = 1:4] label n sprintf("%d", n**2) at n,n center front
splot x*y

How it works…

The first four lines set us up for making a typical contour plot (see Chapter 8, The Third Dimension). The command...