Create app.py

app.py

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+import streamlit as st
+import numpy as np
+import pandas as pd
+import matplotlib.pyplot as plt
+
+# Function to compute present value
+def calculate_pv(cashflows, rate):
+    pv = sum(cf / (1 + rate) ** i for i, cf in enumerate(cashflows))
+    return pv
+
+# Streamlit app layout
+st.title('Cashflow Present Value Calculator')
+
+# Input for the discount rate
+rate = st.slider('Discount Rate (%)', min_value=0.0, max_value=100.0, value=15.0, step=0.1)/100
+
+# Inputs for the number of years
+n = st.number_input("How many years?", min_value = 0, step=1)
+
+# Inputs for the cashflows
+cf_list = [0] * (n+1)  # Asegurémonos de que hay un elemento por cada período
+cf_dict = pd.DataFrame({"cashflows": cf_list}).astype(int)
+cf_df = st.text_area("Enter Cashflows (comma-separated)", value=', '.join(map(str, cf_list)))
+
+cashflows = np.array([float(cf.strip()) for cf in cf_df.split(',')])
+
+# Añadimos un elemento si el número de elementos no coincide con n + 1
+if len(cashflows) != n + 1:
+    st.error("Please enter the correct number of cashflows.")
+    st.stop()
+
+# Button to calculate PV
+if st.button('Calculate Present Value'):
+    pv = calculate_pv(cashflows, rate)
+    st.write(f'The Present Value is: ${pv:,.2f}')
+    
+    # Plotting cashflow diagram
+    fig, ax = plt.subplots(figsize=(8, 6))
+    colors = ['green' if cf > 0 else 'red' for cf in cashflows]
+    ax.plot(range(n+1), cashflows, marker='o', color='b', linestyle='-')
+    ax.fill_between(range(n+1), cashflows, color=colors, alpha=0.3)
+    ax.set_title('Cashflow Diagram')
+    ax.set_xlabel('Period')
+    ax.set_ylabel('Cashflow')
+    for i, cf in enumerate(cashflows):
+        ax.text(i, cf, f'{cf:,.2f}', ha='center', va='bottom')
+    ax.grid(True)