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

Handling financial data

Although gnuplot was originally envisioned as a scientist's companion, it has proven to be a worthy and reliable friend to financial analysts. Financial plotting comes with its own set of complex problems, some of which we'll have to defer to later chapters; in the following figure, we illustrate the basic financial plotting style:

This type of plot will be familiar to you if you follow the stock market.

Getting ready

Sample financial data is essential for illustrating financial plotting. Fortunately, the gnuplot distribution comes with an appropriate sample datafile. In case you don't have it, we have provided a copy called finance.dat. Make sure it's in your current directory so that gnuplot can find it. You are welcome, of course, to use your own data, but it must be in the correct format. Each line of the file represents a separate data point, and consists of (at least) five numbers, separated by spaces: date open low high close.

An example of a line from such a datafile would look similar to the following:

3/11/2011  76.15  76.63  75.2  75.35

How to do it…

Enter the following commands while you are in the directory containing the datafile:

set bars 2
plot [0:100] 'finance.dat' using 0:2:3:4:5 notitle with financebars

How it works…

This makes the conventional financial graph showing the high, low, open, and close prices for a stock. If you are reading this recipe, you no doubt already know why you want this type of plot.

The default size of the tics for the opening and closing prices is quite small; the first command makes it longer. The second command sets the range, chooses the file, and specifies the columns to use for the finance plot.