how to check if a node is already present in Graphviz Python

Question

How to check if a particular node is already present in the graph.

Here is what I have tried.

>>>from graphviz import Digraph
>>>dot = Digraph()
>>>dot.node('solid',xlabel='0')
>>>dot.node('liquid',xlabel='0')
>>>dot.edge('solid','liquid','melt')
>>>print (dot)

digraph {
    solid [xlabel=0]
    liquid [xlabel=0]
    solid -> liquid [label=melt]
}

>>>check = 'solid' in dot
>>>print (solid)

False

As we see here I can't directly check for the node.

I am looking for a way to check if the node has been visited/created before and if that node is visited then increment it's xlabel by 1.

Is there a way to traverse and visit each node in graphviz or do I have to write a separate code to check if a specific node is present?

jur · Accepted Answer · 2019-05-10 12:29:30Z

1

Apparently the .body attribute contains a list with nodes prefixed with tab. Should you could do:

>>>print('\tsolid' in dot.body)

True

answered May 10, 2019 at 12:29

jur

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AlexSin · Accepted Answer · 2020-04-29 07:38:37Z

0

The method worked for me in 2020 is:

if '\tsolid' in dot.source:
    # Here you need to get the line number and know the real xlabel
    dot.body[line_number] = '\tsolid [xlabel='+str(real_xlabel)+']'

answered Apr 29, 2020 at 7:38

AlexSin

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