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.. include:: links.inc
.. _astropy-modeling:
***************************************
Models and Fitting (`astropy.modeling`)
***************************************
Introduction
============
`astropy.modeling` provides a framework for representing models and performing
model evaluation and fitting. A number of predefined 1-D and 2-D models are
provided and the capability for custom, user defined models is supported.
Different fitting algorithms can be used with any model. For those fitters
with the capabilities fitting can be done using uncertainties, parameters with
bounds, and priors.
.. _modeling-using:
Using Modeling
==============
.. toctree::
:maxdepth: 2
Models <models.rst>
Compound Models <compound-models.rst>
Model Parameters <parameters.rst>
Fitting <fitting.rst>
Using Units with Models and Fitting <units.rst>
.. _getting-started-example:
A Simple Example
================
This simple example illustrates defining a model,
calculating values based on input x values, and using fitting data with a model.
.. plot::
:include-source:
import numpy as np
import matplotlib.pyplot as plt
from astropy.modeling import models, fitting
# define a model for a line
line_orig = models.Linear1D(slope=1.0, intercept=0.5)
# generate x, y data non-uniformly spaced in x
# add noise to y measurements
npts = 30
rng = np.random.default_rng(10)
x = rng.uniform(0.0, 10.0, npts)
y = line_orig(x)
y += rng.normal(0.0, 1.5, npts)
# initialize a linear fitter
fit = fitting.LinearLSQFitter()
# initialize a linear model
line_init = models.Linear1D()
# fit the data with the fitter
fitted_line = fit(line_init, x, y)
# plot the model
plt.figure()
plt.plot(x, y, 'ko', label='Data')
plt.plot(x, fitted_line(x), 'k-', label='Fitted Model')
plt.xlabel('x')
plt.ylabel('y')
plt.legend()
.. _advanced_topics:
Advanced Topics
===============
.. toctree::
:maxdepth: 2
Performance Tips <performance.rst>
Extending Models <new-model.rst>
Extending Fitters <new-fitter.rst>
Adding support for units to models <add-units.rst>
Joint Fitting <jointfitter.rst>
Pre-Defined Models
==================
.. To be expanded to include all pre-defined models
Some of the pre-defined models are listed and illustrated.
.. toctree::
:maxdepth: 2
1D Models <predef_models1D.rst>
2D Models <predef_models2D.rst>
Physical Models <physical_models.rst>
Polynomial Models <polynomial_models.rst>
Powerlaw Models <powerlaw_models.rst>
Spline Models <spline_models.rst>
Examples
========
.. toctree::
:maxdepth: 2
Fitting a line <example-fitting-line>
example-fitting-constraints
example-fitting-model-sets
.. TODO list
fitting with masks
fitting with priors
fitting with units
defining 1d model
defining 2d model
fitting 2d model
defining and using a WCS/gWCS model
defining and using a Tabular1D model
statistics functions and how to make your own
compound models
Reference/API
=============
.. toctree::
:maxdepth: 1
reference_api
|
