#!/usr/bin/env python3from mpl_toolkits.mplot3d import Axes3Dfrom matplotlib import cmfrom matplotlib.ticker import LinearLocator, FormatStrFormatterimport matplotlib.pyplot as pltimport numpy as npdef heart_3d(x,y,z):return (x**2+(9/4)*y**2+z**2-1)**3-x**2*z**3-(9/80)*y**2*z**3def plot_implicit(fn, bbox=(-1.5, 1.5)):''' create a plot of an implicit functionfn ...implicit function (plot where fn==0)bbox ..the x,y,and z limits of plotted interval'''xmin, xmax, ymin, ymax, zmin, zmax = bbox*3fig = plt.figure()ax = fig.add_subplot(111, projection='3d')A = np.linspace(xmin, xmax, 100) # resolution of the contourB = np.linspace(xmin, xmax, 40) # number of slicesA1, A2 = np.meshgrid(A, A) # grid on which the contour is plottedfor z in B: # plot contours in the XY planeX, Y = A1, A2Z = fn(X, Y, z)cset = ax.contour(X, Y, Z+z, [z], zdir='z', colors=('r',))# [z] defines the only level to plot# for this contour for this value of zfor y in B: # plot contours in the XZ planeX, Z = A1, A2Y = fn(X, y, Z)cset = ax.contour(X, Y+y, Z, [y], zdir='y', colors=('red',))for x in B: # plot contours in the YZ planeY, Z = A1, A2X = fn(x, Y, Z)cset = ax.contour(X+x, Y, Z, [x], zdir='x',colors=('red',))# must set plot limits because the contour will likely extend# way beyond the displayed level. Otherwise matplotlib extends the plot limits# to encompass all values in the contour.ax.set_zlim3d(zmin, zmax)ax.set_xlim3d(xmin, xmax)ax.set_ylim3d(ymin, ymax)plt.show()if __name__ == '__main__':plot_implicit(heart_3d)