Chapter 1. Prelude: understanding data with gnuplot


This chapter covers

  • Warmup examples
  • What is graphical analysis?
  • What is gnuplot?
Note to Print Book Readers

Some material of a more specialized nature is only available in the e-book version of this book. The e-book also shows all the graphs in color. To get your free e-book in PDF, ePub, or Kindle format, go to to register your print book.

Gnuplot has long been one of the most popular open source programs for plotting and visualizing data. In this book, I want to show you how to use gnuplot to make plots and graphs of your data: both quick and easy graphs for your own use and highly polished graphs for presentations and publications.

But I also want to show you something else: how to solve data-analysis problems using graphical methods. The art of discovering relationships in data and extracting information from it by visual means is called graphical analysis, and I believe gnuplot to be an excellent tool for it.

As a teaser, let’s look at some problems and how you might be able to approach them using graphical methods. The graphs here and in the rest of the book (with very few exceptions) have been, of course, generated with gnuplot.

1.1. A busy weekend

To get a feeling for the kinds of problems you may be dealing with and for the kinds of solutions gnuplot can help you find, let’s look at two examples. Both take place during a long, busy weekend.

1.1.1. Planning a marathon

1.2. What is graphical analysis?

1.3. What is gnuplot?

1.4. Summary