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It's a DAG all the way down

GraphKit is an an understandable and lightweight Python module for building and running ordered graphs of computations. The API posits a fair compromise between features and complexity without precluding any. It might be of use in computer vision, machine learning and other data science domains, or become the core of a custom ETL pipelne.

Here's how to install:

pip install graphkit

OR with dependencies for plotting support (and you need to install Graphviz program separately with your OS tools):

pip install graphkit[plot]

Here's a Python script with an example GraphKit computation graph that produces multiple outputs (a * b, a - a * b, and abs(a - a * b) ** 3):

>>> from operator import mul, sub
>>> from graphkit import compose, operation

>>> # Computes |a|^p.
>>> def abspow(a, p):
...     c = abs(a) ** p
...     return c

>>> # Compose the mul, sub, and abspow operations into a computation graph.
>>> graphop = compose(name="graphop")(
...     operation(name="mul1", needs=["a", "b"], provides=["ab"])(mul),
...     operation(name="sub1", needs=["a", "ab"], provides=["a_minus_ab"])(sub),
...     operation(name="abspow1", needs=["a_minus_ab"], provides=["abs_a_minus_ab_cubed"], params={"p": 3})(abspow)
... )

>>> # Run the graph and request all of the outputs.
>>> out = graphop({'a': 2, 'b': 5})
>>> print(out)
{'a': 2, 'b': 5, 'ab': 10, 'a_minus_ab': -8, 'abs_a_minus_ab_cubed': 512}

>>> # Run the graph and request a subset of the outputs.
>>> out = graphop({'a': 2, 'b': 5}, outputs=["a_minus_ab"])
>>> print(out)
{'a_minus_ab': -8}

As you can see, any function can be used as an operation in GraphKit, even ones imported from system modules!

For debugging the above graph-operation you may plot either the newly omposed graph or the execution plan of the last computation executed, using these methods:

graphop.plot(show=True)                # open a matplotlib window
graphop.plot("graphop.svg")            # other supported formats: png, jpg, pdf, ...
graphop.plot()                         # without arguments return a pydot.DOT object
graphop.plot(solution=out)             # annotate graph with solution values

TIP: The pydot.Dot instances returned by plot() are rendered as SVG in Jupyter/IPython.

Code licensed under the Apache License, Version 2.0 license. See LICENSE file for terms.