Plotting Only One Point in 3D Matplotlib

Question

I'm trying to plot the solution of a linear system with 3 planes, the solution is the point (1,1,1) I've plotted the point with point command but I suspect the point is not in the right place:

ax.plot([1.], [1.], [1.], markerfacecolor='k', markeredgecolor='k', marker='o', markersize=5, alpha=0.6)

Thanks Ok, the code is:

#/usr/bin/env python3
# -*- coding: utf-8 -*-


import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
from sympy.solvers import *
from sympy import *
from matplotlib import rcParams


# Activating LateX
rcParams['text.latex.unicode'] = True
rcParams['text.usetex'] = True
rcParams['text.latex.preamble'] = '\\usepackage{amsthm}', '\\usepackage{amsmath}', '\\usepackage{amssymb}',
'\\usepackage{amsfonts}', '\\usepackage[T1]{fontenc}', '\\usepackage[utf8]{inputenc}'


# Declaring the three planes as functions
f1 = lambda x, y: x + y -1
f2 = lambda x, y: 1 - x + y
f3 = lambda x, y: 1 + x - y

# Declaring symbolic variables
x = Symbol('x')
y = Symbol('y')
z = Symbol('z')

# Solving the linear system
fun1 = x+y-z-1
fun2 = x-y+z-1
fun3 = -x+y+z-1
solucion = solve([fun1, fun2, fun3], [x, y, z])

# Printing the solution
pprint(('Solución Del Sistema es: {}').format(solucion))


# Stablishing our ranges for our variables
x1 = y1 = np.arange(-5, 5, 0.25)
ceros = np.zeros(len(x1))

# Stablishing our meshgrid
x, y = np.meshgrid(x1, y1)

# Our 3D Canvas Figure Plot
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Plotting the 3 planes
ax.plot_surface(x, y, f1(x, y), rstride=1, cstride=1, linewidth=0, antialiased=True, color='blue')
ax.plot_surface(x, y, f2(x, y), rstride=1, cstride=1, linewidth=0, antialiased=True, color='red')
ax.plot_surface(x, y, f3(x, y), rstride=1, cstride=1, linewidth=0, antialiased=True, color='green')
ax.plot([1.], [1.], [1.], markerfacecolor='k', markeredgecolor='k', marker='o', markersize=5, alpha=0.6)

# Putting the limits in the axes
ax.set_xlim(-10, 10)
ax.set_ylim(-10, 10)
ax.set_zlim(-10, 10)

# Writing the axis labels
ax.set_xlabel('x', color='blue')
ax.set_ylabel('y', color='blue')
ax.set_zlabel('z', color='blue')

# Writing The Title of The Plot
ax.set_title(r'$Graphical\; Resolution\; Linear\; System\; 3 \times 3$', fontsize=18)

# Stablishing the plots of our legend labels
blue_proxy = plt.Rectangle((0, 0), 1, 1, fc='b')
red_proxy = plt.Rectangle((0, 0), 1, 1, fc='r')
green_proxy = plt.Rectangle((0, 0), 1, 1, fc='g')
black_proxy = plt.Line2D([0], [0], linestyle="none", marker='o', alpha=0.6, markersize=10, markerfacecolor='black')

# Drawing Our Legend
ax.legend([blue_proxy,red_proxy, green_proxy, black_proxy], [r'$x+y-z=1$',r'$x-y+z=1$', r'$-x+y+z=1$', r'$Sol.\; (1,1,1)$'], numpoints=1, loc='upper left')

plt.show()

An image:

The z-coordinate of the point (1,1,1) is not at the height 1, it is below 0. So, the point is not drawn in the correct place.

Answer 1

I think your code is completely correct. The point IS at its position namely (1,1,1). You can drag the plot to see the point from another angle and you'll find that the point is at a correct position.

Trust yourself! By replacing the z-coordinate of point to maybe 10.0, you'll find that your code is correct.