Creating contour plots

A contour plot displays the isolines of matrix. Isolines are curves where a function of two variables has the same value.

In this recipe we will learn how to create contour plots.

Getting ready

Contours are represented as a contour plot of matrix Z, where Z is interpreted as height with respect to the X-Y plane. Z is of minimum size 2 and must contain at least two different values.

The problem with contour plots is that if they are coded without labeling the isolines, they render pretty useless as we cannot decode the high points from low points or find local minimas.

Here we need to label the contour also. The labeling of isolines can be done either by using labels (clabel()) or colormaps. If your output medium permits the usage of color, colormaps are preferred because viewers will be able to decode data more easily.

The other risk with contour plots is choosing the number of isolines to plot. If we choose too many, the plot becomes too dense to decode, and if we go with...