zfit-interface

Warnings

• breaking As a 0.x.x version library, the API of `zfit-interface` is still under active development and may introduce breaking changes without strict adherence to semantic versioning until a 1.0.0 release.
  Fix: Refer to the GitHub repository and release notes for updates when upgrading to newer 0.x.x versions. Be prepared for potential API adjustments.
• gotcha This library is an 'interface' for `zfit` models, not a standalone fitting library. It requires `zfit` for model definition and `iminuit` (or other supported minimizers) for the actual minimization process. Users must install these dependencies separately.
  Fix: Ensure both `zfit` and `iminuit` are installed alongside `zfit-interface` using `pip install zfit iminuit`.
• gotcha The documentation for `zfit-interface` is currently minimal. Users should be prepared to consult the source code and examples on the GitHub repository for detailed usage patterns and functionality.
  Fix: Refer directly to the official GitHub repository's `examples` directory and source code for the most up-to-date and complete usage information.

Install

• pip install zfit-interface Install latest version

Imports

• Iminuit

  from zfit_interface.minimizer import Iminuit

• ZfitMinuitFitter

  from zfit_interface.fit import ZfitMinuitFitter

Quickstart

This quickstart demonstrates how to define a zfit model and data, then use the `zfit-interface` to fit it with `iminuit`. It involves instantiating the `Iminuit` minimizer wrapper and the `ZfitMinuitFitter`.

import zfit
from zfit.models import Gauss
from zfit.spaces import Space
from zfit_interface.minimizer import Iminuit
from zfit_interface.fit import ZfitMinuitFitter

# 1. Define a zfit model and data
obs = Space('x', limits=(-10, 10))
mu = zfit.Parameter('mu', 0., -1., 1.)
sigma = zfit.Parameter('sigma', 1., 0.1, 10.)
gauss = Gauss(mu=mu, sigma=sigma, obs=obs)
data = gauss.sample(n=1000)

# 2. Instantiate the iminuit minimizer from zfit-interface
minimizer = Iminuit()

# 3. Create the zfit-interface fitter
fitter = ZfitMinuitFitter(minimizer=minimizer)

# 4. Perform the fit
result = fitter.fit(model=gauss, data=data)

print(f"Fit result: {result.params}")
print(f"Minimizer status: {result.info['minuit_minos_status']}")