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Book4_Ch16_Python_Codes/Streamlit_Bk4_Ch16_01.py

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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 plotly.express as px
+
+import numpy as np
+import pandas as pd  
+from sklearn.datasets import load_iris
+
+#%%
+
+# A copy from Seaborn
+iris = load_iris()
+X = iris.data
+y = iris.target
+
+feature_names = ['Sepal length, x1','Sepal width, x2',
+                 'Petal length, x3','Petal width, x4']
+
+# Convert X array to dataframe
+X_df = pd.DataFrame(X, columns=feature_names)
+
+with st.sidebar:
+    st.latex('X = USV^T')
+    st.latex('X = \sum_{j=1}^{D} s_j u_j v_j^T')
+    st.latex('X \simeq \sum_{j=1}^{p} s_j u_j v_j^T')
+
+#%% Original data, X
+
+X = X_df.to_numpy();
+
+U, S, V_T = np.linalg.svd(X, full_matrices=False)
+S = np.diag(S)
+V = V_T.T
+
+with st.sidebar:
+    p = st.slider('Choose p, number of component to approximate X:',
+                  1,4,step = 1)
+
+#%% Approximate X
+
+X_apprx = U[:,0:p]@S[0:p,0:p]@V[:,0:p].T
+X_apprx_df = pd.DataFrame(X_apprx, columns = feature_names)
+
+Error_df = X_df - X_apprx_df
+#%%
+col1, col2, col3 = st.columns(3)
+with col1:
+    st.latex('X')
+    fig_1 = px.imshow(X_df,
+                      color_continuous_scale='RdYlBu_r',
+                      range_color = [0,8])
+
+    fig_1.layout.height = 500
+    fig_1.layout.width = 300
+    fig_1.update_layout(coloraxis_showscale=False)
+    st.plotly_chart(fig_1)
+
+with col2:
+    
+    st.latex('\hat{X}')
+    fig_2 = px.imshow(X_apprx_df,
+                      color_continuous_scale='RdYlBu_r',
+                      range_color = [0,8])
+    
+    fig_2.layout.height = 500
+    fig_2.layout.width = 300
+    fig_2.update_layout(coloraxis_showscale=False)
+    st.plotly_chart(fig_2)
+    
+with col3:
+    
+    st.latex('X - \hat{X}')
+    fig_3 = px.imshow(Error_df,
+                      color_continuous_scale='RdYlBu_r',
+                      range_color = [0,8])
+    
+    fig_3.layout.height = 500
+    fig_3.layout.width = 300
+    fig_3.update_layout(coloraxis_showscale=False)
+    st.plotly_chart(fig_3)
+