#!/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 function fn ...implicit function (plot where fn==0) bbox ..the x,y,and z limits of plotted interval''' xmin, xmax, ymin, ymax, zmin, zmax = bbox*3 fig = plt.figure() ax = fig.add_subplot(111, projection='3d') A = np.linspace(xmin, xmax, 100) # resolution of the contour B = np.linspace(xmin, xmax, 40) # number of slices A1, A2 = np.meshgrid(A, A) # grid on which the contour is plotted for z in B: # plot contours in the XY plane  X, Y = A1, A2  Z = 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 z for y in B: # plot contours in the XZ plane  X, Z = A1, A2  Y = 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 plane  Y, Z = A1, A2  X = 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)