Finance Core Library

This is a lightweight core finance library for computing and plotting common financial metrics like Net Present Value (NPV) and Internal Rate of Return (IRR). The goal is to build a solid foundation for financial computation with test coverage, modularity, and educational clarity.

Features

• getNPV(cashflows, discount_rate): Computes Net Present Value via formula
• npf_getNPV(cashflows, discount_rate): Computes Net Present Value via numpy_financial
• getIRR(cashflows): Estimates Internal Rate of Return via numpy_financial.
• irr_bisection(cashflows, ...): Estimates Internal Rate of Return via bisection.
• irr_newton_raphson(cashflows, ...): Estimates Internal Rate of Return via Newton-Raphson method.
• plot_npv_curve(cashflow, ...): Plots NPV vs. Discount Rate with optional IRR annotation and save-to-file.
• Command-line interface with flags like --rate_min, --save_path, and --return_irr.
• Built for education, modularity, and public showcase (with full test coverage).

Structure

• finance-core/: Core logic for IRR, NPV, and more
  • irr.py: defines internal rate of return methods, one via numpy_finance, one via bisection.
  • npv.py: defines net present value methods, one via formula calculation, one via numpy_finance.
  • plot_npv.py: defines npv plotting method.
• tests/: Unit tests for validating financial functions
  • test_irr.py: unittest for irr.py
  • test_npv.py: unittest for npv.py
  • test_plot_npv.py: unittest for plot_npv.py
• docs/: Project documentation and finance notes
  • README.md: this file.

Getting Started

1. To set up dependency, use:
   pip install -r requirements.txt

2. To run tests, use:
   python -m unittest tests/test_<module>.py
   or simply run all tests:
   python -m unittest discover tests

3. To run functions, use:
   python -m finance_core.<module> <input>

Usage

Run from the project root using the -m flag.

Plotting NPV

python -m finance_core.plot_npv -100 50 30 40 --return_irr --save_path npv_plot.png

Arguments:

• <cashflows> (required): A list of cashflows, e.g. -1000 500 400
• --rate_min: Minimum discount rate to plot (default: -0.5)
• --rate_max: Maximum discount rate to plot (default: 0.5)
• --steps: Number of steps to evaluate NPV curve (default: 100)
• --return_irr: Print estimated IRR
• --save_path: Save plot to file instead of displaying
• --compare: Plot a secondary curve with a differents set of cashflow to compare with.

Sample Plots

Plot one cashflow:

Compare two sets of cashflows visually:

Running IRR Calculation

python -m finance_core.irr "-1000,300,500,200"

Running NPV Calculation

python -m finance_core.npv -100 50 30 40 15%

Author

Laura Nan - Work in Progress. This project is part of a structured self-study journey toward Quantitative & Computational Finance. It emphasizes mastery through implementation, testing, and real-world modeling scenarios.