Advanced usage¶

This Jupyter notebook shows some advanced features of the Python package mevis. The .ipynb file can be found here.

The central function of this package is mv.plot for visualizing OpenCog’s AtomSpaces. Internally it calls three functions that are also relevant for users:

mv.filter to reduce the AtomSpace to a selection of some Atoms of interest.

Its arguments enable various ways of filtering:
- target select some Atoms
- context decides whether the selection is expanded to some context around the Atoms
  - "atom": no extension of the selection
  - "in": extension to incoming Atoms, can be done n times by passing a tuple ("in", n)
  - "out": extension to outgoing Atoms, can be done n times with ("out", n)
  - "in_out": extension to incoming and outgoing Atoms, can be done n times with ("in_out", n), which means an extension to a neighborhood of size n
  - "subgraph": extension to the entire subgraph, which means using the selected Atoms as roots and following their outgoing edges until reaching only leaves
- mode decides whether the selected Atoms are included to or excluded from the output
mv.convert to transform an AtomSpace to a normal graph with two types of nodes, which correspond to OpenCog’s Node and Link types.
- Several arguments allow to add annotations to the graph, e.g. node label, size, color and shape, or edge label and color. These annotations are recognized by the plotting function and translated into visual elements and their appearance.
mv.layout to calculate x and y coordinates for each node in the graph.
- Several layout methods are available. Some depend on Graphviz (e.g. neato, dot, twopi), others come with NetworkX (e.g. bipartite, shell, spring).

These three functions can also be called by the user, for example to apply multiple filtering steps one after another, or to export the resulting annotated graph to a gml file for external tools. Note that mv.plot can also use a graph object as input, but most arguments are ignored in that case, because no filter, convert and layout steps are performed in that case.

[1]:

import mevis as mv
from opencog.atomspace import types

Advanced usage¶

Load an AtomSpace¶

Filter an AtomSpace¶

1) By an Atom or a list of Atoms¶

2) By an Atom name or a list of Atom names¶

3) By an Atom type or a list of Atom types¶

4) By a function that returns True or False¶

5) By a combination of the previous¶

Convert an AtomSpace to a graph¶

Layout a graph¶

Explicitly use filter, convert and layout¶

Implicitly use filter, convert and layout¶