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Range sets
==========
.. highlight:: python
Cluster node names being typically indexed, common node sets rely heavily on
numerical range sets. The :mod:`.RangeSet` module provides two public classes
to deal directly with such range sets, :class:`.RangeSet` and
:class:`.RangeSetND`, presented in the following sections.
.. _class-RangeSet:
RangeSet class
--------------
The :class:`.RangeSet` class implements a mutable, ordered set of cluster node
indexes (over a single dimension) featuring a fast range-based API. This class
is used by the :class:`.NodeSet` class (see :ref:`class-NodeSet`). Since
version 1.6, :class:`.RangeSet` actually derives from the standard Python set
class (`Python sets`_), and thus provides methods like :meth:`.RangeSet.union`,
:meth:`.RangeSet.intersection`, :meth:`.RangeSet.difference`,
:meth:`.RangeSet.symmetric_difference` and their in-place versions
:meth:`.RangeSet.update`, :meth:`.RangeSet.intersection_update`,
:meth:`.RangeSet.difference_update()` and
:meth:`.RangeSet.symmetric_difference_update`.
In v1.9, the implementation of zero-based padding of indexes (e.g. `001`) has
been improved. The inner set contains indexes as strings with the padding
included, which allows the use of mixed length zero-padded indexes (eg. using
both `01` and `001` is valid and supported in the same object). Prior to v1.9,
zero-padding was a simple display feature of fixed length per
:class:`.RangeSet` object, and indexes where stored as integers in the inner
set.
To iterate over indexes as strings with zero-padding included, you can now
iterate over the :class:`.RangeSet` object (:meth:`.RangeSet.__iter__()`),
or still use the :meth:`.RangeSet.striter()` method which has not changed.
To iterate over the set's indexes as integers, you may use the new method
:meth:`.RangeSet.intiter()`, which is the equivalent of iterating over the
:class:`.RangeSet` object before v1.9.
.. _class-RangeSetND:
RangeSetND class
----------------
The :class:`.RangeSetND` class builds a N-dimensional RangeSet mutable object
and provides the common set methods. This class is public and may be used
directly, however we think it is less convenient to manipulate that
:class:`.NodeSet` and does not necessarily provide the same one-dimension
optimization (see :ref:`class-NodeSet-nD`). Several constructors are
available, using RangeSet objects, strings or individual multidimensional
tuples, for instance::
>>> from ClusterShell.RangeSet import RangeSet, RangeSetND
>>> r1 = RangeSet("1-5/2")
>>> list(r1)
['1', '3', '5']
>>> r2 = RangeSet("10-12")
>>> r3 = RangeSet("0-4/2")
>>> r4 = RangeSet("10-12")
>>> print r1, r2, r3, r4
1,3,5 10-12 0,2,4 10-12
>>> rnd = RangeSetND([[r1, r2], [r3, r4]])
>>> print rnd
0-5; 10-12
>>> print list(rnd)
[('0', '10'), ('0', '11'), ('0', '12'), ('1', '10'), ('1', '11'), ('1', '12'), ('2', '10'), ('2', '11'), ('2', '12'), ('3', '10'), ('3', '11'), ('3', '12'), ('4', '10'), ('4', '11'), ('4', '12'), ('5', '10'), ('5', '11'), ('5', '12')]
>>> r1 = RangeSetND([(0, 4), (0, 5), (1, 4), (1, 5)])
>>> len(r1)
4
>>> str(r1)
'0-1; 4-5\n'
>>> r2 = RangeSetND([(1, 4), (1, 5), (1, 6), (2, 5)])
>>> str(r2)
'1; 4-6\n2; 5\n'
>>> r = r1 & r2
>>> str(r)
'1; 4-5\n'
>>> list(r)
[('1', '4'), ('1', '5')]
.. _Python sets: http://docs.python.org/library/sets.html
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