.. module:: bettermoments.methods
.. methods

API
===

Here we describe all the functions used to collapse the spectral cube which are
typically called by the command line interface. However, importing these into
your workflow may be useful.

In general, for the generated moment maps, ``MX``, where ``X`` is an integer
denotes a statistical moment. For the non-traditional methods, ``v0``, ``dV``
and ``Fnu`` represent the line center, width and peak, respectively.

.. note::
    The convolution for ``smooththreshold`` is currently experimental and is
    work in progress. If things look suspicious, please raise an issue.

.. note::
    Most ``collapse_*`` functions accept an optional ``acf`` keyword. When
    supplied, the uncertainty maps are propagated through the full spectral
    noise covariance :math:`C_{ij} = \sigma^2 \, \rho(|i - j|)` rather than
    its diagonal, correctly accounting for channel-to-channel noise
    correlation (e.g. from Hanning smoothing in the imaging pipeline). The
    ACF can be estimated directly from the cube with
    :func:`bettermoments.estimate_spectral_acf`, or enabled from the command
    line with the ``--acf`` flag. Only the uncertainty maps are affected — the
    moment values themselves are unchanged.



Moment Maps
-----------

Implementation of traditional moment-map methods. See the `CASA documentation
<https://casa.nrao.edu/docs/CasaRef/image.moments.html>`_ for more information.

.. autofunction:: bettermoments.methods.collapse_zeroth

.. autofunction:: bettermoments.methods.collapse_first

.. autofunction:: bettermoments.methods.collapse_second

.. autofunction:: bettermoments.methods.collapse_eighth

.. autofunction:: bettermoments.methods.collapse_ninth

.. autofunction:: bettermoments.methods.collapse_maximum


Non-Traditional Methods
-----------------------

.. autofunction:: bettermoments.methods.collapse_quadratic

.. autofunction:: bettermoments.methods.collapse_width

.. autofunction:: bettermoments.methods.collapse_percentiles


(Higher Order) Gaussian Fits
----------------------------

.. autofunction:: bettermoments.methods.collapse_gaussian

.. autofunction:: bettermoments.methods.collapse_gaussthick

.. autofunction:: bettermoments.methods.collapse_gausshermite

.. autofunction:: bettermoments.methods.collapse_doublegauss

.. autofunction:: bettermoments.methods.collapse_analytical