mirror of
https://github.com/Visualize-ML/Book4_Power-of-Matrix.git
synced 2026-02-03 18:43:34 +08:00
53 lines
1.4 KiB
Python
53 lines
1.4 KiB
Python
|
|
###############
|
|
# Authored by Weisheng Jiang
|
|
# Book 4 | From Basic Arithmetic to Machine Learning
|
|
# Published and copyrighted by Tsinghua University Press
|
|
# Beijing, China, 2022
|
|
###############
|
|
|
|
# Bk4_Ch3_01.py
|
|
|
|
import matplotlib.pyplot as plt
|
|
import numpy as np
|
|
|
|
p_values = [0.05, 0.2, 0.5, 1, 1.5, 2, 4, 8, np.inf]
|
|
|
|
x1 = np.linspace(-2.5, 2.5, num=101);
|
|
x2 = x1;
|
|
|
|
xx1, xx2 = np.meshgrid(x1,x2)
|
|
|
|
fig, axes = plt.subplots(ncols=3,nrows=3,
|
|
figsize=(12, 12))
|
|
|
|
for p, ax in zip(p_values, axes.flat):
|
|
|
|
if np.isinf(p):
|
|
zz = np.maximum(np.abs(xx1),np.abs(xx2))
|
|
else:
|
|
zz = ((np.abs((xx1))**p) + (np.abs((xx2))**p))**(1./p)
|
|
|
|
# plot contour of Lp
|
|
ax.contourf(xx1, xx2, zz, 20, cmap='RdYlBu_r')
|
|
|
|
# plot contour of Lp = 1
|
|
ax.contour (xx1, xx2, zz, [1], colors='k', linewidths = 2)
|
|
|
|
# decorations
|
|
|
|
ax.axhline(y=0, color='k', linewidth = 0.25)
|
|
ax.axvline(x=0, color='k', linewidth = 0.25)
|
|
ax.set_xlim(-2.5, 2.5)
|
|
ax.set_ylim(-2.5, 2.5)
|
|
ax.spines['top'].set_visible(False)
|
|
ax.spines['right'].set_visible(False)
|
|
ax.spines['bottom'].set_visible(False)
|
|
ax.spines['left'].set_visible(False)
|
|
ax.set_xlabel('$x_1$')
|
|
ax.set_ylabel('$x_2$')
|
|
ax.set_title('p = ' + str(p))
|
|
ax.set_aspect('equal', adjustable='box')
|
|
|
|
plt.show()
|