We installed matplotlib and IPython in Chapter 1, Getting Started with Python Libraries. Please go back to that chapter if you need to. The procedural MATLAB-like matplotlib API is considered by many as simpler to use than the object-oriented API, so we will demonstrate this procedural API first. To create a very basic plot in matplotlib, we need to invoke the plot() function in the matplotlib.pyplot subpackage. This function produces a two-dimensional plot for a single list or multiple lists of points with known x and y coordinates.

Optionally, we can pass a format parameter, for instance, to specify a dashed line style. The list of format options and parameters for the plot() function is pretty long, but easy to look up with the following commands:

$ ipython -pylab
In [1]: help(plot)

In this example, we will plot two lines: one with a solid line style (the default) and the other with a dashed line style.

The following demo code is in the basic_plot.py file in this...