Update app.py

app.py

@@ -1,39 +1,40 @@
-from flask import Flask, render_template, request, jsonify
+import streamlit as st
 import numpy as np
+import pandas as pd
 import matplotlib.pyplot as plt
 
-app = Flask(__name__)
+# Function to compute present value
+def calculate_pv(cashflows, rate):
+    pv = sum(cf / (1 + rate) ** i for i, cf in enumerate(cashflows))
+    return pv
 
-def calcular_vpn(n, r, cash_flow):
-    descuento = 1 / ((1 + r) ** np.arange(1, n + 1))
-    vpn = np.sum(cash_flow * descuento)
-    return vpn
+# Streamlit app layout
+st.title('Cashflow Present Value Calculator')
 
-@app.route('/')
-def index():
-    return render_template('index.html')
+# Input for the discount rate
+rate = st.number_input('Discount Rate (%)', min_value=0.0, max_value=100.0, value=15.0, step=0.1)/100
 
-@app.route('/calcular', methods=['POST'])
-def calcular():
-    data = request.get_json()
-    n = int(data['n'])
-    r = float(data['r'])
-    cash_flow = np.array(data['cash_flow'])
-    
-    vpn = calcular_vpn(n, r, cash_flow)
-    
-    plt.figure(figsize=(10, 6))
-    plt.plot(np.arange(1, n + 1), cash_flow, marker='o')
-    plt.xlabel('Años')
-    plt.ylabel('Cash Flow')
-    plt.title('Flujo de Efectivo')
-    plt.grid(True)
-    
-    # Guardar el gráfico como imagen
-    img_path = 'static/plot.png'
-    plt.savefig(img_path)
-    
-    return jsonify({'vpn': vpn, 'plot_path': img_path})
+# Inputs for the number of years
+n = st.number_input("How many years?", min_value = 0, step=1)
 
-if __name__ == '__main__':
-    app.run(debug=True)
+# Inputs for the cashflows
+cf_list = [0] * (n+1)
+cf_dict = pd.DataFrame({"cashflows": cf_list}).astype(int)
+cf_df = st.data_editor(cf_dict.T)
+
+cashflows = np.array(cf_df.values[0])
+
+# Button to calculate PV
+if st.button('Calculate Present Value'):
+    pv = calculate_pv(cashflows, rate)
+    st.write(f'The Present Value is: ${pv:,.2f}')
+    
+    # Prepare data for the plot
+    colors = ['green' if cf > 0 else 'red' for cf in cashflows]
+    plt.scatter(range(n+1), cashflows, c=colors)
+    plt.title('Cashflow Diagram')
+    plt.xlabel('Period')
+    plt.ylabel('Cashflow')
+    for i, cf in enumerate(cashflows):
+        plt.annotate(f'{cf:,.2f}', (i, cf), textcoords="offset points", xytext=(0,n), ha='center')
+    st.pyplot(plt)