pygrank-f

This is an experimental forward-oriented programming variation of pygrank; a package for node ranking in large graphs. pygrank-f provides a simpler interface on top of the same core, but does not support all main library capabilities. New features successfully developed in this repository will be eventually fleshed out in the interface of the source package.

Dependencies: pyfop,pyyaml,numpy,networkx
Development: Emmanouil (Manios) Krasanakis
Contant: [email protected]

💿 Large graphs
🚀 Fast processing
🍪 Easy to use
🧩 Modular interface
🧬 Organic backpropagation
🌐 Share experiments as web resources

Quickstart

Graph filters are called via pygrankf.steps interface that sequences the consecutive operations used to process the first step's data. Tuning should always be the last step and is applied on any arguments declared to be Tunable.

import pygrankf as pgf

communities = pgf.load("citeseer")
for name, community in communities.items():
    exclude, test = community.split(0.5)
    train, validation = exclude.split(0.9)
    # define a sequence of steps
    result = pgf.steps(
        train,
        pgf.filter,
        pgf.tune(validation=validation, metric=pgf.mabs, exclude=train)
    ).call()
    pgf.print(name, pgf.auc(test, result, exclude=exclude))

Instead of having tunable graph filter parameters, you can also set specific ones, alongside any other arguments you might want to pass to your filter, such as those controlling its convergence:

.call(parameters=pgf.PageRank(alpha=0.85), errtype=pgf.mabs, tol=1.E-9)

In this case, the tuning will warn you that there is nothing to be tuned and you can safely remove it from steps. Other filters can be declared by setting the appropriate parameters. You can see all parameters you can set by calling .get_input_context() instead of .call().

You might want to define parameterized data preprocessing to be tuned on some objective, such as making node ranking fairness-aware. It suffices for this definition to produce the first step like this:

original = pgf.pagerank(train).call(spectrum="symmetric")  # power method implementation of pagerank 
fair_result = pgf.steps(
    pgf.neural(train, original, sensitive),
    pgf.pagerank,
    pgf.tune(optimizer=pgf.tfsgd,
             metric=lambda *args: min(pgf.prule(args[1], sensitive, exclude), 1)-pgf.l1(args[1], original, exclude))
).call(spectrum="symmetric")  # theoretical results only for symmetric spectrums

The above snippet sets up a neural graph filter prior generation scheme, which takes any number of graph signals to account for - typically those used to define the metric objective. The optimizer this time is pgf.tfsgd, which the package provides as an alternative to its own default blackbox optimization. This requires comparatively few algorithm reruns for convex objectives via tensorflow's autograd.