Delete Book4_Ch13_Python_Codes directory

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Iris Series: Visualize Math -- From Arithmetic Basics to Machine Learning
2025-02-01 17:01:57 +08:00
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parent 24ffdbf527
commit a722f54863
4 changed files with 0 additions and 345 deletions

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###############
# Authored by Weisheng Jiang
# Book 4 | From Basic Arithmetic to Machine Learning
# Published and copyrighted by Tsinghua University Press
# Beijing, China, 2022
###############
# Bk4_Ch13_01.py
import numpy as np
import matplotlib.pyplot as plt
A = np.array([[1.25, -0.75],
[-0.75, 1.25]])
xx1, xx2 = np.meshgrid(np.linspace(-8, 8, 9), np.linspace(-8, 8, 9))
num_vecs = np.prod(xx1.shape);
thetas = np.linspace(0, 2*np.pi, num_vecs)
thetas = np.reshape(thetas, (-1, 9))
thetas = np.flipud(thetas);
uu = np.cos(thetas);
vv = np.sin(thetas);
fig, ax = plt.subplots()
ax.quiver(xx1,xx2,uu,vv,
angles='xy', scale_units='xy',scale=1,
edgecolor='none', facecolor= 'b')
plt.ylabel('$x_2$')
plt.xlabel('$x_1$')
plt.axis('scaled')
ax.set_xlim([-10, 10])
ax.set_ylim([-10, 10])
ax.grid(linestyle='--', linewidth=0.25, color=[0.5,0.5,0.5])
ax.set_xticks(np.linspace(-10,10,11));
ax.set_yticks(np.linspace(-10,10,11));
plt.show()
# Matrix multiplication
V = np.array([uu.flatten(),vv.flatten()]).T;
W = V@A;
uu_new = np.reshape(W[:,0],(-1, 9));
vv_new = np.reshape(W[:,1],(-1, 9));
fig, ax = plt.subplots()
ax.quiver(xx1,xx2,uu,vv,
angles='xy', scale_units='xy',scale=1,
edgecolor='none', facecolor= 'b')
ax.quiver(xx1,xx2,uu_new,vv_new,
angles='xy', scale_units='xy',scale=1,
edgecolor='none', facecolor= 'r')
plt.ylabel('$x_2$')
plt.xlabel('$x_1$')
plt.axis('scaled')
ax.set_xlim([-10, 10])
ax.set_ylim([-10, 10])
ax.grid(linestyle='--', linewidth=0.25, color=[0.5,0.5,0.5])
ax.set_xticks(np.linspace(-10,10,11));
ax.set_yticks(np.linspace(-10,10,11));
plt.show()
fig, ax = plt.subplots()
ax.quiver(xx1*0,xx2*0,uu,vv,
angles='xy', scale_units='xy',scale=1,
edgecolor='none', facecolor= 'b')
ax.quiver(xx1*0,xx2*0,uu_new,vv_new,
angles='xy', scale_units='xy',scale=1,
edgecolor='none', facecolor= 'r')
plt.ylabel('$x_2$')
plt.xlabel('$x_1$')
plt.axis('scaled')
ax.set_xlim([-2, 2])
ax.set_ylim([-2, 2])
ax.grid(linestyle='--', linewidth=0.25, color=[0.5,0.5,0.5])
ax.set_xticks(np.linspace(-2,2,5));
ax.set_yticks(np.linspace(-2,2,5));
plt.show()

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###############
# Authored by Weisheng Jiang
# Book 4 | From Basic Arithmetic to Machine Learning
# Published and copyrighted by Tsinghua University Press
# Beijing, China, 2022
###############
# Bk4_Ch13_02.py
import numpy as np
import matplotlib.pyplot as plt
def visualize(X_circle,X_vec,title_txt):
fig, ax = plt.subplots()
plt.plot(X_circle[0,:], X_circle[1,:],'k',
linestyle = '--',
linewidth = 0.5)
plt.quiver(0,0,X_vec[0,0],X_vec[1,0],
angles='xy', scale_units='xy',scale=1,
color = [0, 0.4392, 0.7529])
plt.quiver(0,0,X_vec[0,1],X_vec[1,1],
angles='xy', scale_units='xy',scale=1,
color = [1,0,0])
plt.axvline(x=0, color= 'k', zorder=0)
plt.axhline(y=0, color= 'k', zorder=0)
plt.ylabel('$x_2$')
plt.xlabel('$x_1$')
ax.set_aspect(1)
ax.set_xlim([-2.5, 2.5])
ax.set_ylim([-2.5, 2.5])
ax.grid(linestyle='--', linewidth=0.25, color=[0.5,0.5,0.5])
ax.set_xticks(np.linspace(-2,2,5));
ax.set_yticks(np.linspace(-2,2,5));
plt.title(title_txt)
plt.show()
theta = np.linspace(0, 2*np.pi, 100)
circle_x1 = np.cos(theta)
circle_x2 = np.sin(theta)
V_vec = np.array([[np.sqrt(2)/2, -np.sqrt(2)/2],
[np.sqrt(2)/2, np.sqrt(2)/2]])
X_circle = np.array([circle_x1, circle_x2])
# plot original circle and two vectors
visualize(X_circle,V_vec,'Original')
A = np.array([[1.25, -0.75],
[-0.75, 1.25]])
# plot the transformation of A
visualize(A@X_circle, A@V_vec,'$A$')
#%% Eigen deomposition
# A = V @ D @ V.T
lambdas, V = np.linalg.eig(A)
D = np.diag(np.flip(lambdas))
V = V.T # reverse the order
print('=== LAMBDA ===')
print(D)
print('=== V ===')
print(V)
# plot the transformation of V.T
visualize(V.T@X_circle, V.T@V_vec,'$V^T$')
# plot the transformation of D @ V.T
visualize(D@V.T@X_circle, D@V.T@V_vec,'$\u039BV^T$')
# plot the transformation of V @ D @ V.T
visualize(V@D@V.T@X_circle, V@D@V.T@V_vec,'$V\u039BV^T$')
# plot the transformation of A
visualize(A@X_circle, A@V_vec,'$A$')

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###############
# Authored by Weisheng Jiang
# Book 4 | From Basic Arithmetic to Machine Learning
# Published and copyrighted by Tsinghua University Press
# Beijing, China, 2022
###############
# Bk4_Ch13_03.py
import numpy as np
import matplotlib.pyplot as plt
theta = np.deg2rad(30)
r = 0.8 # 1.2, scaling factor
R = np.array([[np.cos(theta), -np.sin(theta)],
[np.sin(theta), np.cos(theta)]])
S = np.array([[r, 0],
[0, r]])
A = R@S
# A = np.array([[1, -1],
# [1, 1]])
Lamb, V = np.linalg.eig(A)
theta_array = np.arange(0,np.pi*2,np.pi*2/18)
colors = plt.cm.rainbow(np.linspace(0,1,len(theta_array)))
fig, ax = plt.subplots()
for j, theat_i in enumerate(theta_array):
# initial point
x = np.array([[5*np.cos(theat_i)],
[5*np.sin(theat_i)]])
plt.plot(x[0],x[1],
marker = 'x',color = colors_j,
markersize = 15)
# plot the initial point
x_array = x
for i in np.arange(20):
x = A@x
x_array = np.column_stack((x_array,x))
colors_j = colors[j,:]
plt.plot(x_array[0,:],x_array[1,:],
marker = '.',color = colors_j)
plt.axis('scaled')
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.axvline(x=0,color = 'k')
ax.axhline(y=0,color = 'k')

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###############
# Authored by Weisheng Jiang
# Book 4 | From Basic Arithmetic to Machine Learning
# Published and copyrighted by Tsinghua University Press
# Beijing, China, 2022
###############
import streamlit as st
import numpy as np
import plotly.express as px
import pandas as pd
def bmatrix(a):
"""Returns a LaTeX bmatrix
:a: numpy array
:returns: LaTeX bmatrix as a string
"""
if len(a.shape) > 2:
raise ValueError('bmatrix can at most display two dimensions')
lines = str(a).replace('[', '').replace(']', '').splitlines()
rv = [r'\begin{bmatrix}']
rv += [' ' + ' & '.join(l.split()) + r'\\' for l in lines]
rv += [r'\end{bmatrix}']
return '\n'.join(rv)
with st.sidebar:
st.latex(r'''
A = \begin{bmatrix}
a & b\\
c & d
\end{bmatrix}''')
a = st.slider('a',-2.0, 2.0, step = 0.1, value = 1.0)
b = st.slider('b',-2.0, 2.0, step = 0.1, value = 0.0)
c = st.slider('c',-2.0, 2.0, step = 0.1, value = 0.0)
d = st.slider('d',-2.0, 2.0, step = 0.1, value = 1.0)
#%%
x1_ = np.linspace(-1, 1, 11)
x2_ = np.linspace(-1, 1, 11)
xx1,xx2 = np.meshgrid(x1_, x2_)
X = np.column_stack((xx1.flatten(), xx2.flatten()))
# st.write(X)
A = np.array([[a, b],
[c, d]])
X = X@A
# st.write(len(X))
#%%
color_array = np.linspace(0,1,len(X))
# st.write(color_array)
X = np.column_stack((X, color_array))
df = pd.DataFrame(X, columns=['z1','z2', 'color'])
#%% Scatter
st.latex('A = ' + bmatrix(A))
fig = px.scatter(df,
x="z1",
y="z2",
color='color',
color_continuous_scale = 'rainbow')
fig.update_layout(
autosize=False,
width=500,
height=500)
fig.add_hline(y=0, line_color = 'black')
fig.add_vline(x=0, line_color = 'black')
fig.update_xaxes(range=[-3, 3])
fig.update_yaxes(range=[-3, 3])
fig.update_coloraxes(showscale=False)
st.plotly_chart(fig)