Announcement: NetworkX 2.2
==========================

We're happy to announce the release of NetworkX 2.2!
NetworkX is a Python package for the creation, manipulation, and study of the
structure, dynamics, and functions of complex networks.

For more information, please visit our `website <http://networkx.github.io/>`_
and our `gallery of examples
<https://networkx.github.io/documentation/latest/auto_examples/index.html>`_.
Please send comments and questions to the `networkx-discuss mailing list
<http://groups.google.com/group/networkx-discuss>`_.

Highlights
----------

This release is the result of X of work with over X pull requests by
X contributors. Highlights include:


Improvements
------------
Each function that uses random numbers now uses a `seed` argument to control
the random number generation (RNG). By default the global default RNG is
used. More precisely, the `random` package's default RNG or the numpy.random
default RNG. You can also create your own RNG and pass it into the `seed`
argument. Finally, you can use an integer to indicate the state to set for
the RNG. In this case a local RNG is created leaving the global RNG untouched.
Some functions use `random` and some use `numpy.random`, but we have written
a translater so that all functions CAN take a `numpy.random.RandomState`
object. So a single RNG can be used for the entire package.

Cyclic references between graph classes and views have been removed to ease
subclassing without memory leaks. Graphs no longer hold references to views.

Cyclic references between a graph and itself have been removed by eliminating
G.root_graph. It turns out this was an avoidable construct anyway.

GraphViews have been reformulated as functions removing much of the subclass
trouble with the copy/to_directed/subgraph methods. It also simplifies the
graph view code base and API. There are now three function that create
graph views: generic_graph_view(graph, create_using), reverse_view(digraph)
and subgraph_view(graph, node_filter, edge_filter).

GraphML can now be written with attributes using numpy numeric types.
In particular, np.float64 and np.int64 no longer need to convert to Python
float and int to be written. They are still written as generic floats so
reading them back in will not make the numpy values.

A generator following the Stochastic Block Model is now available.

New function `all_topolgical_sort` to generate all possible top_sorts.

New functions for tree width and tree decompositions.

Functions for Clauset-Newman-Moore modularity-max community detection.

Functions for small world analysis, directed clustering and perfect matchings.

The shortest_path generic and convenience functions now have a `method`
parameter to choose between dijkstra and bellmon-ford in the weighted case.
Default is dijkstra (which was the only option before).

API Changes
-----------
empty_graph has taken over the functionality from
nx.convert._prep_create_using which was removed.

The `create_using` argument (used in many functions) should now be a
Graph Constructor like nx.Graph or nx.DiGraph.
It can still be a graph instance which will be cleared before use, but the
preferred use is a constructor.

New Base Class Method: update
H.update(G) adds the nodes, edges and graph attributes of G to H.
H.update(edges=e, nodes=n) add the edges and nodes from containers e and n.
H.update(e), and H.update(nodes=n) are also allowed.
First argument is a graph if it has `edges` and `nodes` attributes.
Otherwise the first argument is treated as a list of edges.

The bellman_ford predecessor dicts had sentinal value `[None]` for
source nodes. That has been changed so source nodes have pred value '[]'


Deprecations
------------

Graph class method `fresh_copy` - simply use `__class__`.
The GraphView classes are deprecated in preference to the function
interface. Specifically, `ReverseView` and `ReverseMultiView` are
replaced by `reverse_view`. `SubGraph`, `SubDiGraph`, `SubMultiGraph`
and `SubMultiDiGraph` are replaced by `subgraph_view`.
And `GraphView`, `DiGraphView`, `MultiGraphView`, `MultiDiGraphView`
are derecated in favor of `generic_graph_view(graph, create_using)`.


Contributors to this release
----------------------------

<output of contribs.py>


Pull requests merged in this release
------------------------------------

<output of contribs.py>
