Real World Instrumentation with Python

Displaying Simulation Data

A simulation can generate a lot of useful data, but just looking at a file with a list of numbers isn’t as intuitive as seeing a graph of the data. In this section I will show you how to use the data generated by a simulator to create interesting and useful graphical output in the form of data plots.

We’ll focus on gnuplot, a venerable tool that has been available for Unix and Linux systems for many years. There is also a Windows version available, and both can work with Python to display dynamically generated data. Later, in Chapter 13, we’ll look at user interfaces and more sophisticated ways to generate graphical output, but this is a good place to begin.

gnuplot

gnuplot is a powerful and well-established graphical plotting tool that is capable of generating graphical output ranging from simple line graphs to complex data visualizations. Although it was originally developed for Unix, there is a Windows version available as well. gnuplot has a serviceable built-in command-line-style user interface and the ability to load plot command and data files. It can also use so-called pipes for its command input, thus allowing other applications to drive the plot display. This section briefly describes two methods to allow Python programs to send data and commands to gnuplot for display. The first is a simple demonstration of Python’s popen() method. While this method is straightforward and easy to implement, it does nothing to assist you with gnuplot; it just sends ...