One tool for working with finance in Python is QuantLib. If you're building a basic model, there's a good chance it's already implemented in QuantLib; if you're working with something more advanced, it provides a good starting point.
Here's a basic example of options pricing. (You can download the example here, or see it on github.) This is the input to QuantLib:

The script reads in this data and returns a vanilla option price. This is using the Black-Scholes-Merton process for pricing, but many other options models are built in - the Heston/Hull White models and numerical models, for example. Here's where the computations are done:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | # basic option
payoff = PlainVanillaPayoff(opt_type, strike)
exercise = EuropeanExercise(maturity)
europeanOption = VanillaOption(payoff, exercise)
# handle setups
underlyingH = QuoteHandle(SimpleQuote(underlying))
flatTermStructure = YieldTermStructureHandle(FlatForward(settlementDate,
riskFreeRate,
dayCounter))
dividendYield = YieldTermStructureHandle(FlatForward(settlementDate,
dividendYield,
Actual365Fixed()))
flatVolTS = BlackVolTermStructureHandle(BlackConstantVol(settlementDate,
calendar,
volatility,
dayCounter))
# done
bsmProcess = BlackScholesMertonProcess(underlyingH, dividendYield,
flatTermStructure, flatVolTS)
# method: analytic
europeanOption.setPricingEngine(AnalyticEuropeanEngine(bsmProcess))
value = europeanOption.NPV()
return value
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The main part of this code is selecting what kind of model to use - computing the value of a vanilla option just scratches the surface of what QuantLib can do.
The output, with real time stock prices from Yahoo finance:

To use QuantLib with DataNitro, you need to compile Python bindings for it. Instructions for this are available on the QuantLib site. A compiled version of QuantLib for Python is also available with the enterprise version of DataNitro.