Python for Finance - Second Edition

Introduction to SciPy

The following are a few examples based on the functions enclosed in the SciPy module. The sp.npv() function estimates the present values for a given set of cash flows with the first cash flow happening at time zero. The first input value is the discount rate, and the second input is an array of all cash flows.

The following is one example. Note that the sp.npv() function is different from the Excel npv() function. We will explain why this is so in Chapter 3, Time Value of Money:

>>>import scipy as sp
>>>cashflows=[-100,50,40,20,10,50]
>>>x=sp.npv(0.1,cashflows)
>>>round(x,2)
>>>31.41

The sp.pmt() function is used to answer the following question.

What is the monthly cash flow to pay off a mortgage of $250,000 over 30 years with ...