metatable 1.1.2

Extensible table data structure that supports concise workflow descriptions via user-defined combinators.

Extensible table data structure that supports the introduction of user-defined workflow combinators and the use of these combinators in concise workflow descriptions.

Package Installation and Usage

The package is available on PyPI:

python -m pip install metatable

The library can be imported in the usual ways:

import metatable
from metatable import *

Examples

This library makes it possible to work with tabular data that is represented as a list of lists (i.e., each row is a list of column values and a table is a list of rows):

>>> from metatable import *
>>> t = metatable([['a', 0], ['b', 1], ['c', 2]])
>>> list(iter(t))
[['a', 0], ['b', 1], ['c', 2]]

All rows in a metatable instance can be updated in-place using a symbolic representation (implemented using the symbolism library) of the transformation that must be applied to each row. For example, the transformation {1: column(0)} indicates that the value in the column having index 1 (i.e., the right-hand column) should be replaced with the value in the column having index 0 (i.e., the left-hand column):

>>> t.update({1: column(0)})
[['a', 'a'], ['b', 'b'], ['c', 'c']]

It is also possible to perform an update that removes rows based on a condition. The condition in the example below is the symbolic expression column(1) > symbol(0) (constructed using the symbolism library):

>>> from symbolism import symbol
>>> t = metatable([['a', 0], ['b', 1], ['c', 2]])
>>> t.update_filter({0: column(1)}, column(1) > symbol(0))
[[1, 1], [2, 2]]

There is also support for working with a tabular data set in which there is a header row containing column names:

>>> t = metatable([['char', 'num'], ['a', 0], ['b', 1]], header=True)
>>> t.update({1: column(0)})
[['char', 'num'], ['a', 'a'], ['b', 'b']]

See the module documentation for additional examples.

Documentation

The documentation can be generated automatically from the source files using Sphinx:

cd docs
python -m pip install -r requirements.txt
sphinx-apidoc -f -E --templatedir=_templates -o _source .. ../setup.py && make html

Testing and Conventions

All unit tests are executed and their coverage is measured when using nose (see setup.cfg for configuration details):

python -m pip install nose coverage
nosetests --cover-erase

Alternatively, all unit tests are included in the module itself and can be executed using doctest:

python metatable/metatable.py -v

Style conventions are enforced using Pylint:

python -m pip install pylint
pylint metatable

Contributions

In order to contribute to the source code, open an issue or submit a pull request on the GitHub page for this library.

Versioning

The version number format for this library and the changes to the library associated with version number increments conform with Semantic Versioning 2.0.0.