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57 lines
1.6 KiB
Markdown
57 lines
1.6 KiB
Markdown
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---
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title: "Tree-based Plots in NetworkX"
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date: 2022-01-02T20:36:41-05:00
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draft: false
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tags: ["Python"]
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math: false
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---
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A graph in D3 and NetworkX can be represented as a JSON file.
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Example:
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```json
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{
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"nodes": [
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{"id": 1, "name": "A"},
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{"id": 2, "name": "B"},
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{"id": 3, "name": "C"}
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],
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"links": [
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{"source": 1,"target": 2},
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{"source": 1,"target": 3}
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]
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}
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```
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The `nodes` entry in the JSON is a list containing a `node` object. Each `node` object has a unique id and a name which can appear inside the node in the drawing.
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The `links` entry in the JSON is a list of `link` objects which each denote a (directed) edge between a source and target id.
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To run the following script you'll need `graphwiz` installed on the system. You'll also need to have the python packages `networkx` and `pydot`.
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```python
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import networkx as nx
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from networkx.readwrite import json_graph
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from networkx.drawing.nx_pydot import graphviz_layout
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import matplotlib.pyplot as plt
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# Replace graph_json variable with JSON representation of graph
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graph_json = {"nodes": [{"id": 1, "name": "A"},{"id": 2, "name": "B"}],"links": [{"source":1,"target":2}]}
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node_labels = {node['id']:node['name'] for node in graph_json['nodes']}
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for n in graph_json['nodes']:
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del n['name']
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g = json_graph.node_link_graph(graph_json, directed=True, multigraph=False)
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pos = graphviz_layout(g, prog="dot")
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nx.draw(g.to_directed(), pos, labels=node_labels, with_labels=True)
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plt.show()
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```
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Given the JSON from the top of the post it'll produce:
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