.. 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.
.. note::
A number of significant changes have been made to the internals that have been
documented in more detail in :doc:`changes_for_4`. The main change is that
combining model classes no longer is supported. (Combining model
instances is still very much supported!)
.. _modeling-using:
Using Modeling
==============
.. toctree::
:maxdepth: 2
Models
Compound Models
Model Parameters
Fitting
Using Units with Models and Fitting
Changes in v4.0
.. _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
np.random.seed(10)
x = np.random.uniform(0.0, 10.0, npts)
y = line_orig(x)
y += np.random.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
Extending Models
Extending Fitters
Adding support for units to models
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
2D Models
Physical Models
Polynomial Models
Examples
========
.. toctree::
:maxdepth: 2
Fitting a 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