[PYTHON] Use directional graphs with networkx
NetworkX is a Python package for working with graphs.
I recently learned how to get other nodes related to a particular node in the NetworkX directed graph DiGraph, so I'll write it for later.
The assumed effective graph looks like this.
Focusing on node C, B is the parent of C and D is the child of C. Also, A and B are ancestors of C, and D and E are descendants of C.
First, let's import NetworkX and create an empty directional graph.
>>> import networkx as nx
>>> g = nx.DiGraph()
Next, create the graph in the above figure with ʻadd_path`. When you create a path, it seems that you can create a node without explicitly adding it.
>>> g.add_path(["A","B","C","D","E"])
>>> g.nodes()
['E', 'C', 'D', 'A', 'B']
Now, to get the parent and child of C, use the methods predecessors and successors of graph g. The result is returned as list, as there can be multiple parents and children each.
>>> g.predecessors("C")
['B']
>>> g.successors("C")
['D']
On the other hand, to get the ancestors and offspring of C, use the functions descendants and ʻansstors. The result is returned with set`.
>>> nx.descendants(g, "C")
{'D', 'E'}
>>> nx.ancestors(g, "C")
{'A', 'B'}
Note that for parents and children, the method returns the result as list, for ancestors and offspring, the function is used, and the result is returned as set.
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