CODEWITHSUNDEEP
pythongraphgraphvizpygraphviz
abolotnov
abolotnov

Reputation: 4332

GraphViz - generate graph on top of assorted list of nodes/edges with python?

I have a list of items that relate to each other, I know they end up building a graph but the data is not sorted in any way.

PMO-100 -> SA-300
SA-100 -> SA-300
SA-100 -> SA-200
PMO-100 -> SA-100

In python examples for graphViz api I realize that you can pretty much generate a graph if you know it's top node and can run down the levels and build all the relations.

Since I'm getting an assorted list (I only know that it is a graph since all relations are figured from a single point) - is there a way to build a graph on top of this data?

Update: the first comment to this question identifies I haven't correctly explained what I'm after. Indeed the following code gets you a proper graph:

gr = pydot.Dot(graph_type='digraph')
    for link in graph.links:
        edge = pydot.Edge(link.outwardIssue.key, link.inwardIssue.key)
        gr.add_edge(edge)
    gr.write('graph.png',format='png')

my question really is - how can I color-rode individual nodes or change type of arrow for a specific edge?

Upvotes: 0

Views: 3293

Answers (3)

Aziz Alto
Aziz Alto

Reputation: 20341

Try out pygraph package, it produces a directed graph based on relation statements (data). No matter if the data are sorted or not.

So (as in your case) if we have the following data (in a triple relation), it is easy to produce the corresponding graph:

First way

s1 = "PMO-100 -> SA-300"
s2 = "SA-100 -> SA-300"
s3 = "SA-100 -> SA-200"
s4 = "PMO-100 -> SA-100"

from pygraph.dgraph import PyGraph

g = PyGraph()

g.add_relation(s1)
g.add_relation(s2)
g.add_relation(s3)
g.add_relation(s4)

g.draw_graph(label=False)

It will produce:

enter image description here

Or you can even read the relations from a file.

Second way

Say, you have data.txt:

PMO-100 -> SA-300
SA-100 -> SA-300
SA-100 -> SA-200
PMO-100 -> SA-100

It is even easier in 4 loc,:

from pygraph.dgraph import PyGraph

g = PyGraph()

g.file_relations("data.txt")

g.draw_graph(label=False)

In both ways the result is the same:

enter image description here

Upvotes: 0

Dr Sokoban
Dr Sokoban

Reputation: 1638

How to change color of nodes:

node.attr["color"] = 'red'

to change the shape of arrowhead, same method

edge.attr["arrowhead"] = "..."

Upvotes: 0

rainer
rainer

Reputation: 7099

There is no need to identify a top node for graphviz. Just add all Nodes and edges and let it do the rest. For example:

import pydot
graph = pydot.Dot('graphname', graph_type='digraph') 
pmo100 = pydot.Node("PMO-100")
sa300 = pydot.Node("SA-300")
sa100 = pydot.Node("SA-100")
sa200 = pydot.Node("SA-200")
graph.add_edge(pydot.Edge(pmo100, sa300))
graph.add_edge(pydot.Edge(sa100, sa300))
graph.add_edge(pydot.Edge(sa100, sa200))
graph.add_edge(pydot.Edge(pmo100, sa100))
graph.write_png('example1_graph.png')

This will result in the following image:

result

You can find more info at http://pythonhaven.wordpress.com/2009/12/09/generating_graphs_with_pydot/

Upvotes: 1

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