PyXIRR Financial Functions

Warnings

• gotcha XIRR calculation requires both positive and negative cash flows. If a series of cash flows contains only positive or only negative values, the `xirr` function will raise an exception.
  Fix: Ensure your input cash flows include at least one positive and one negative value. You can suppress the exception by using the `silent=True` parameter: `xirr(dates, amounts, silent=True)`.
• gotcha The Multiple IRR problem can occur when cash flow signs change more than once. PyXIRR attempts to find a solution around a default guess (0.1, similar to Excel) and, if unsuccessful, tries other attempts, ultimately selecting the lowest IRR to be conservative.
  Fix: Be aware of this behavior for non-conventional cash flow series. If specific IRR solutions are expected, manual inspection or alternative initial guesses might be necessary, though PyXIRR's approach often yields a reasonable result.
• gotcha The `npv` function in PyXIRR defaults to starting from zero (NumPy compatible). Excel's `NPV` function, however, typically starts summation from the first period.
  Fix: If exact Excel compatibility for `npv` is required, use the `start_from_zero=False` parameter: `pyxirr.npv(rate, values, start_from_zero=False)`.
• gotcha While PyXIRR provides high performance, it might have a 'certain conversion cost' compared to direct NumPy operations, especially when passing large amounts of data between Python and the Rust core.
  Fix: For optimal performance with large datasets, consider passing data in formats that minimize conversion overhead, such as NumPy arrays or pandas DataFrames, as PyXIRR is optimized to work efficiently with these.

Install

• pip install pyxirr Install stable version

Imports

• xirr

  from pyxirr import xirr

• DayCount

  from pyxirr import DayCount

  Used for specifying day count conventions like ACT_360 or 30E/360.
• All functions (e.g., fv, npv)

  import pyxirr
  pyxirr.fv(...)

Quickstart

This example demonstrates how to calculate the Extended Internal Rate of Return (XIRR) using a list of dates and corresponding cash flow amounts. PyXIRR functions can accept various input formats, including separate lists, iterables of tuples, NumPy arrays, or pandas DataFrames.

from datetime import date
from pyxirr import xirr

dates = [
    date(2020, 1, 1),
    date(2021, 1, 1),
    date(2022, 1, 1)
]
amounts = [-1000, 750, 500]

# Calculate XIRR with columnar data
result = xirr(dates, amounts)
print(f"Calculated XIRR: {result:.4f}")

# XIRR also accepts iterables of tuples or pandas DataFrames
# from pyxirr import xnpv
# npv_result = xnpv(0.05, dates, amounts)
# print(f"Calculated XNPV: {npv_result:.2f}")