Current status of sub-packages

Astropy has benefited from the addition of widely tested legacy code, as well as new development, resulting in variations in stability across sub-packages. This document summarizes the current status of the Astropy sub-packages, so that users understand where they might expect changes in future, and which sub-packages they can safely use for production code.

Note that until version 1.0, even sub-packages considered Mature could undergo some user interface changes as we work to integrate the packages better. Thus, we cannot guarantee complete backward-compatibility between versions at this stage.

The classification is as follows:

	Planned
	Actively developed, be prepared for possible significant changes
	Reasonably stable, no major changes likely
	Mature

The current planned and existing sub-packages are:

Sub-Package		Comments
astropy.constants		Constants have been changed to Quantity objects in v0.2.
astropy.convolution		New top-level package in v0.3 (was previously part of astropy.nddata). No major changes in v0.4.
astropy.coordinates		New in v0.2, major changes in v0.4. Subsequent versions should maintain a stable/backwards-compatible API.
astropy.cosmology		Incremental improvements since v0.1, but mostly stable API. Pure functional interface deprecated in v0.4.
astropy.io.ascii		Originally developed as asciitable, and has maintained a stable API.
astropy.io.fits		Originally developed as pyfits, and retains an API consistent with the standalone version.
astropy.io.misc		The functionality that is currently present is stable, but this sub-package will likely see major additions in future.
astropy.io.votable		Originally developed as vo.table, and has a stable API.
astropy.modeling		New in v0.3
astropy.nddata		In development, and does not yet contain much functionality apart from a base class for N-dimensional datasets.
astropy.photometry
astropy.stats		Still in development, and does not yet contain much functionality.
astropy.table		Incremental improvements since v0.1, but mostly stable API.
astropy.time		Incremental improvements since v0.1, but mostly stable API.
astropy.units		New in v0.2. Adapted from pnbody and integrated into Astropy.
astropy.utils		This sub-package contains mostly utilities destined for use in other parts of Astropy, and is not yet stable.
astropy.vo		Virtual Observatory service access and validation. Currently, only Simple Cone Search and SAMP are supported.
astropy.wcs		Originally developed as pywcs, and has a stable API for now. However, there are plans to generalize the WCS interface to accommodate non-FITS WCS transformations, and this may lead to small changes in the user interface.