metaset 1.0.3

Links

• Package on PyPI: http://pypi.python.org/pypi/metaset/

• Source on GitHub: http://github.com/Polyconseil/metaset/

• Build on Travis CI: http://travis-ci.org/lionel-panhaleux/metaset/

Quickstart

Install the package from PyPI, using pip:

pip install metaset

Or from GitHub:

$ git clone git://github.com/lionel-panhaleux/metaset.git

Import it in your code:

from metaset import MetaSet

Usage is quite straight forward, basic set operations are supported via the binary operators + - | ^.

>>> MetaSet(a={1, 2}, b={3}) | MetaSet(b={4}, c={5})
{'a': {1, 2}, 'b': {3, 4}, 'c': {5}}

Detailed considerations

They are two ways to consider the “dict of sets” notion, differing on how you handle the empty values for keys.

The easiest idea is to consider that a key with no content is non-existent. This is how the dictset package is implemented.

In this alternative implementation, we chose to keep the empty keys as meaningful elements, allowing for smart unions and intersections.

>>> MetaSet(a={1}) | Metaset(a={2}, b=set())
{'a': {1, 2}, 'b': set()}

>>> MetaSet(a={1}) & Metaset(a={2}, b={3})
{'a': set()}

So, beware of how empty-keys are handled, and consider using dictset if it is a better match for your use case. The behavior for subtraction and symmetric difference, although sound on a mathematical point of view, may not be what you want.

>>> MetaSet(a={1}) - MetaSet(a={1})
{'a': set()}

>>> MetaSet(a={1}) ^ MetaSet(a={1})
{'a': set()}