Update app.py

app.py

@@ -1,3 +1,54 @@
 import streamlit as st
+import numpy as np
+import pandas as pd
+import matplotlib.pyplot as plt
 
-st.write("Hello World")
+
+# Streamlit app layout
+
+st.title("Paying insurance with my savings account 💼")
+
+# Create the inputs (A, r, n)
+
+A = st.number_input("How much do you want monthly?")
+
+r = st.number_input("What is the interest rate?")
+
+n = int(st.number_input("For how many months?", step = 1))
+
+
+# Create the outputs
+
+Pn_d = (A * 12 / r) * (1 - (1 / (1 + r/12)**n))
+
+Pn_c = (A / (np.exp(r/12) - 1)) * (1 - np.exp(- r * n / 12))
+
+
+# Print the outputs
+
+st.write(f"The value of P is {Pn_d:,.2f} with discrete model")
+
+st.write(f"The value of P is {Pn_c:,.2f} with continuous model")
+
+
+# Draw the plot
+
+cf_list = [-Pn_c] + [A] * n
+cf_dict = pd.DataFrame({"cashflows": cf_list}).astype(float)
+cf_df = st.dataframe(cf_dict.T)
+
+# Prepare data for the plot
+colors = ["green" if cf > 0 else "red" for cf in cf_dict.cashflows]
+plt.scatter(range(n + 1), cf_dict.cashflows, c=colors)
+plt.title("Cashflow Diagram")
+plt.xlabel("Period")
+plt.ylabel("Cashflow")
+for i, cf in enumerate(cf_dict.cashflows):
+    plt.annotate(
+        f"{cf:,.2f}",
+        (i, cf),
+        textcoords="offset points",
+        xytext=(0, n),
+        ha="center",
+    )
+st.pyplot(plt)