Hi all,

Here is a first draft of a release announcement. It is a little long and wordy, so please feel free to make changes. I did some minor curation of the “minor or bugfix changes” list, but I’m sure we could do more. 



The yt community is proud to announce the release of yt 3.1.

yt (http://yt-project.org) is an open source, community-developed
toolkit for analysis and visualization of volumetric data of all
types, with a particular emphasis on astrophysical simulations and
nuclear engineering simulations.

This is a scheduled feature release. Highlighted changes in yt 3.1:

Major changes:

* The RADMC-3D export analysis module has been updated.
* Performance improvements for grid frontends.
* Added a frontend for Dark Matter-only NMSU Art simulations.
* The absorption spectrum generator has been updated.
* The PerspectiveCamera has been updated and a new SphericalCamera has been added.
* The unit system now supports unit equivalencies and has improved support for MKS units.
* Data object selection can now be chained, allowing selecting based on multiple constraints.
* Added the ability to manually override the simulation unit system.
* The documentation has been reorganized and has seen substantial improvements. 

Minor or bugfix changes:

* The Gadget InternalEnergy and StarFormationRate fields are now read in with the correct units.
* Substantial improvements for the PPVCube analysis module and support for FITS datasets.
* The center of a PlotWindow plot can now be set to the maximum or minimum of any field.
* Fixes for yt testing infrastructure.
* Projections are now performed using an explicit path length field for all coordinate systems.
* An example notebook for simulations using the OWLS data format has been added to the documentation.
* Fix for the camera.draw_line function.
* Minor fixes and improvements for yt plots.
* Significant documentation reorganization and improvement.
* Fixed a conflict in the CFITSIO library used by the x-ray photon simulator analysis module.
* Miscellaneous code cleanup.
* yt now hooks up to the python logging infrastructure in a more standard fashion, avoiding issues 
  with yt logging showing up with using other libraries.
* A bug in the calculation of the plot bounds for off-axis slice plots has been fixed.
* Improvements for the yt-rockstar interface.
* Fix issues with plot positioning with saving to postscript or encapsulated postscript.
* It is now possible to supply a default value for get_field_parameter.
* A bug in the interpretation of the units of RAMSES simulations has been fixed.
* Improvements and bugfixes for the halo analysis framework.
* Fix issues with the default setting for the "center" field parameter.
* yt can now be run in parallel on a subset of available processors using an MPI subcommunicator.
* Fix for incorrect units when loading an Athena simulation as a time series.
* Improved support for Enzo 3.0 simulations that have not produced any active particles.
* Fix for periodic radius vector calculation.
* Improvements for the Maestro and Castro frontends.
* Clump finding is now supported for more generic types of data.
* Fix unit consistency issue when mixing dimensionless unit symbols.
* Improved memory footprint in the photon_simulator.
* Large grids in Athena datasets produced by the join_vtk script can now be optionally split, 
  improving parallel performance. 
* Slice plots now accept a “data_source" keyword argument.
* Corrected inconsistent octrees in the RAMSES frontend.
* Nearest neighbor distance field added.
* Improvements for the ORION2 frontend.
* Enzo 3.0 frontend can now read active particle attributes that are arrays of any shape.
* A “setup_function" has been added to the LightRay initializer.
* Fixes for accessing deposit fields for FLASH data. 
* Added tests for ORION datasets containing sink and star particles.
* Added wrapper functions for numpy array manipulation functions.
* Added support for packed HDF5 Enzo datasets.

A more comprehensive list of the changes in this release can be found at http://yt-project.org/docs/3.1/reference/changelog.html

Standard Installation Methods

As with previous releases, you can install yt from source using one of 
the following methods. 

1) From the install script (http://yt-project.org/#getyt):

# Installation

$ wget http://hg.yt-project.org/yt/raw/stable/doc/install_script.sh
$ bash install_script.sh

# Update

$ yt update

2) From pip (source or binary wheel, see below for more details):

# Installation

$ pip install yt

# Update

$ pip install -U yt

3) From the Anaconda Python Distribution (https://store.continuum.io/cshop/anaconda/): 

# Installation

$ conda install yt

# Update 

$ conda update yt

Note that it might take a day or two for the conda package to be updated.

Installing Binary Packages via pip

New to this release is the ability to install binary packages (“wheels”) using
pip on Windows and Mac OS X (64-bit only for both). This has the advantage 
of not needing to install yt from source using a proper compiler setup, which
has caused occasional problems on both of these platforms and prevented us
from installing yt easily on other Python distributions. 

We have so far been able to install and run the binary distribution via pip on the 
following platforms and Python stacks:

Windows x86_64: 

* Enthought Canopy Python (https://www.enthought.com/products/canopy/)
* WinPython (http://winpython.sourceforge.net/

Mac OS X x86_64:

* Enthought Canopy Python (https://www.enthought.com/products/canopy/)
* Homebrew Python (http://brew.sh/)
* Python.org Python
* Mac OS X’s system Python
* MacPorts Python (https://www.macports.org/)

This is somewhat experimental, so other distributions may work (or not), 
please submit bug reports or successes to the mailing list or to the Bitbucket
issues page (http://bitbucket.org/yt_analysis/yt/issues). 

All distributions must be Python v. 2.7. The requirements for installing yt 
via this method are the same as from source:

* NumPy
* h5py
* HDF5
* SymPy
* Matplotlib
* IPython (not required, but strongly recommended)

To install a new version of yt on one of these platforms, simply do 

$ pip install yt

and you should get the binary distribution automatically. Also, if your 
python installation is system-wide (e.g., the Mac system Python) 
you might need to run pip with administrator privileges. 

For more information, including more installation instructions, links to
community resources, and information on contributing to yt’s
development, please see the yt homepage at http://yt-project.org and
the documentation for yt-3.1 at http://yt-project.org/docs/3.1.

yt is the product of a large community of developers and users and we
are extraordinarily grateful for and proud of their contributions. Please 
forward this announcement on to any interested parties.

As always, if you have any questions, concerns, or run into any trouble 
updating please don't hesitate to send a message to the mailing list or 
stop by our IRC channel.

Thank you,

The yt development team