Python Anytree - Is not of type 'NodeMixin' error

[georgebijum]

I am trying to build a Hierarchy from the below csv data:

Child,Parent,IsActive
11074165,11018432,NO
11094122,11033371,NO
11020499,11018277,NO
11018432,11020499,NO

Below is the code snippet

nodes = {}
with open("SampleHierarchy.csv", "r") as f:
    csv_reader = csv.DictReader(f)
    for row in csv_reader:
        #print(row['Code'], row['Parent'],row['IsActive'])
        childItem=row['Code']
        parentItem=row['Parent']
        nodes[childItem] = Node(childItem, parent=parentItem)

But getting the Error:

Error:
*Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 880, in runfile
    execfile(filename, namespace)
  File "C:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)
  File "CounterpartyHierarchyTree.py", line 37, in <module>
    Node(childItem, parent=parentItem)
  File "C:\ProgramData\Anaconda3\lib\site-packages\anytree\node\node.py", line 77, in __init__
    self.parent = parent
  File "C:\ProgramData\Anaconda3\lib\site-packages\anytree\node\nodemixin.py", line 127, in parent
    raise TreeError(msg)
anytree.node.exceptions.TreeError: Parent node '11018432' is not of type 'NodeMixin'.*

Larz60+ write May-05-2022, 10:36 AM:
Please post all code, output and errors (it it's entirety) between their respective tags. Refer to BBCode help topic on how to post. Use the "Preview Post" button to make sure the code is presented as you expect before hitting the "Post Reply/Thread" button.
Fixed for you this time. Please use BBCode tags on future posts.

[Gribouillis]

With your code, parentItem is a string read in the csv file. But the Node() constructor obviously expects parent to have a subtype of NodeMixin. It is probable that None is accepted too as parent node.

I suggest sorting the nodes topologically before instanciating the Nodes, unless you can update the parent node after creation, in which case you could create all the nodes without parent and update their parents afterwards.

[georgebijum]

With your code, parentItem is a string read in the csv file. But the Node() constructor obviously expects parent to have a subtype of NodeMixin. It is probable that None is accepted too as parent node.

I suggest sorting the nodes topologically before instanciating the Nodes, unless you can update the parent node after creation, in which case you could create all the nodes without parent and update their parents afterwards.

Thanks for the update .Will sort the data as you mentioned.
On Node() constructor expectation - will you be able to share few lines of code that will handle the issue

Thanks

[Gribouillis]

will you be able to share few lines of code that will handle the issue

The anytree documentation about the «parent» attribute suggests that you can set the attribute after creation, so I suggest something like

nodes = {}
with open("SampleHierarchy.csv", "r") as f:
    # creation step
    csv_reader = csv.DictReader(f)
    for row in csv_reader:
        for item in (row['Code'], row['Parent']):
            if item and (item not in nodes):
                nodes[item] = Node(item)
    # parent setting step
    f.seek(0)
    csv_reader = csv.DictReader(f)
    for row in csv_reader:
        c, p = row['Code'], row['Parent']
        if c and p:
            nodes[c].parent = nodes[p]