Create app.py

app.py

@@ -0,0 +1,60 @@
+import numpy as np
+import streamlit as st
+import scipy.stats
+import matplotlib.pyplot as plt
+from matplotlib import rc
+
+st.subheader("Bayesian Coin Toss")
+st_col = st.columns(1)[0]
+
+n_samples = st.slider('N_samples', 2, 40, 1)
+n_heads = st.slider('N_heads', 2, 40, 1)
+alpha = st.slider('Alpha', 0.5, 5.0, 0.5)
+beta = st.slider('Beta', 0.5, 5.0, 0.5)
+
+theta = np.linspace(0.01,0.99,100)
+rc('font', size=20)
+# rc('text', usetex=True)
+fig, ax = plt.subplots(figsize=(12,6))
+axs = ax.twinx()
+
+def Bernoulli(theta, N, h):
+    return (theta ** h) * ((1-theta) ** (N-h))
+
+def coin_toss(N, h, alpha, beta):
+    Likelihood = [Bernoulli(t,N,h) for t in theta]
+    
+    ax.cla();axs.cla()
+    ax.plot(theta, Likelihood, label='Likelihood',color='b');
+    axs.plot(theta, scipy.stats.beta.pdf(theta, alpha,beta), label='Prior',color='k');
+    ax.set_xlabel('p(head)');
+    ax.vlines(h/N, *ax.get_ylim(), linestyle='--',label='MLE', color='b')
+    axs.text(h/N,2,'MLE', color='b')
+    
+    axs.plot(theta, [scipy.stats.beta.pdf(t, h+alpha, N-h+beta) for t in theta], color='r')
+    ax.text(theta[0], Likelihood[0],'Likelihood', color='b')
+    axs.text(theta[-5], scipy.stats.beta.pdf(theta, alpha,beta)[-5],'Prior')
+    axs.text(alpha/(alpha+beta)-0.1,1,'Prior mean')
+    axs.text(theta[0],scipy.stats.beta.pdf(theta[0], h+alpha, N-h+beta),'Posterior',color='r')
+    axs.text((h+alpha)/(N+alpha+beta)-0.1,3,'Post. Mean',color='r')
+    ax.vlines(alpha/(alpha+beta), *ax.get_ylim(), linestyle='--',label='Prior mean',color='k')
+    ax.vlines((h+alpha)/(N+alpha+beta), *ax.get_ylim(), linestyle='--',label='Post. Mean',color='r')
+    # ax.set_title(f"n_samples={int(N)}, n_heads={int(h)}");
+    ax.tick_params(axis='y', colors='b')
+    axs.tick_params(axis='y', colors='r')
+    ax.set_ylabel('Likelihood',color='b')
+    axs.set_ylabel('Prior/Posterior', color='r', rotation=270, labelpad=30)
+    return fig
+
+
+
+with st_col:
+    st.pyplot(coin_toss(n_samples, n_heads, alpha, beta))
+    
+hide_streamlit_style = """
+            <style>
+            #MainMenu {visibility: hidden;}
+            footer {visibility: hidden;}
+            </style>
+            """
+st.markdown(hide_streamlit_style, unsafe_allow_html=True)