That line is only for jupyter notebooks, if you are using another editor, you'll use: plt.show() at the end of all your plotting commands to have the figure pop up in another window. There are two ...

The first call to matshow() re-enables interactive mode after it has been disabled by matplotlib.interactive(False). In a Jupyter notebook, this has the result of a figure not intended for display ...

It is possible to set a logarithmic scale for one or both axes. This functionality is in fact only one application of a more general transformation system in Matplotlib. Each of the axes' scales are ...