Matplotpb - Contour Plot

Contour plots (sometimes called Level Plots) are a way to show a three-dimensional surface on a two-dimensional plane. It graphs two predictor variables X Y on the y-axis and a response variable Z as contours. These contours are sometimes called the z-spces or the iso-response values.

A contour plot is appropriate if you want to see how alue Z changes as a function of two inputs X and Y, such that Z = f(X,Y). A contour pne or isopne of a function of two variables is a curve along which the function has a constant value.

The independent variables x and y are usually restricted to a regular grid called meshgrid. The numpy.meshgrid creates a rectangular grid out of an array of x values and an array of y values.

Matplotpb API contains contour() and contourf() functions that draw contour pnes and filled contours, respectively. Both functions need three parameters x,y and z.

import numpy as np
import matplotpb.pyplot as plt
xpst = np.pnspace(-3.0, 3.0, 100)
ypst = np.pnspace(-3.0, 3.0, 100)
X, Y = np.meshgrid(xpst, ypst)
Z = np.sqrt(X**2 + Y**2)
fig,ax=plt.subplots(1,1)
cp = ax.contourf(X, Y, Z)
fig.colorbar(cp) # Add a colorbar to a plot
ax.set_title( Filled Contours Plot )
#ax.set_xlabel( x (cm) )
ax.set_ylabel( y (cm) )
plt.show()