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

Plotting with dates and times

gnuplot is capable of handling data plotted along a date/time axis and can understand and display dates and times in a variety of formats.

Getting ready

If you are plotting data versus time, you are almost certainly dealing with data tabulated in a file. We have supplied a small file for this recipe called timedat.dat; it consists of a few lines of data, each line containing a date, time, and a number to be plotted. The dates are in the form day/month/2-digit-year, and the times are in the form hour:minute. Following is the first line:

1/1/11 19:00 72.01

The following figure shows plotting with dates using gnuplot:

Note that the tics along the bottom axis are labeled as dates.

How to do it…

Following is the script that we used to get the previous figure:

set xdata time
set timefmt "%d/%m/%y %H:%M"
set format x "%d/%m/%y"
plot 'timedat.dat' using 1:3 with linespoints

How it works…

When dealing with date/time data, you must always alert gnuplot to this with set xdata time...