Getting started
===============
The main commands to use BNDL are ``bndl-compute-shell`` and ``bndl-compute-workers``.


ComputeContext
--------------
The main entry point for using BNDL Compute is an instance of :class:`bndl.compute.context.ComputeContext`.
This class provides methods to load :doc:`./datasets` on which :doc:`./transformations` can be
applied. See also :doc:`./context`.


Starting the Compute shell
--------------------------
The BNDL Compute Shell is an interactive python shell (using ipython if installed) which starts
local workers and/or connects with worker seed nodes.

.. program-output:: bndl-compute-shell --help

By default the Compute shell starts workers as ``bndl-compute-workers`` unless ``--seeds`` is set.

The shell (with ipython) after start::
   
   $ bndl-compute-shell 
   Python 3.5.2+ (default, Nov  7 2016, 07:16:13) 
   Type "copyright", "credits" or "license" for more information.
   
   IPython 5.0.0 -- An enhanced Interactive Python.
   ?         -> Introduction and overview of IPython's features.
   %quickref -> Quick reference.
   help      -> Python's own help system.
   object?   -> Details about 'object', use 'object??' for extra details.
   
   
            ___ _  _ ___  _
   Welcome | _ ) \| |   \| |
   to the  | _ \ .` | |) | |__
           |___/_|\_|___/|____| shell.
   
   Running BNDL version 0.3.2.dev1.
   ComputeContext available as ctx.
   
   In [1]: 


Starting Compute workers
------------------------
Workers can be started with ``bndl-compute-workers``:

.. program-output:: bndl-compute-workers --help


Connecting workers and the driver node
--------------------------------------
By default as many workers as there are CPU cores (as indicated by ``os.cpu_count()``) are started.
Set ``--listen-addresses`` to a (space separated) list of host[:port] values to bind the hosts to
a certain host (and port). The default port for BNDL is 5000. Free ports are automatically selected
for the workers. Set ``--seeds`` to one or more addresses of nodes which help new nodes find the
others.


From a python script
--------------------
Python scripts can use the ``ctx`` global from ``bndl.compute.run`` to acquire a ComputeContext_:

.. code:: pycon

    >>> from bndl.compute.run import ctx
    >>> ctx.range(1000).map(str).map(len).stats()
    <Stats count=1000, mean=2.890000000000001, min=1.0, max=3.0, var=0.11789999999999999, stdev=0.3433656942677879, skew=-3.2053600735213332, kurt=10.25131920569249>