Giving Hierarchy to a list of Titles

I have this list in python

titles = [
    '13.3. Risk',
    '13.3.1. Strategy',
    'SubStrategy',
    '13.3.2. Token',
    'Material',
    'Impact',
    'Aling'
]

And I would like to create hierarchy resulting in something like this:

|_'13.3. Risk'
   |____'13.3.1. Strategy' 
   |     |____'SubStrategy' 
   |____'13.3.2. Token' 
        |____'Material' 
        |____'Impact' 
        |____'Aling'

I have tried regexp, and also the library anytree but I am not getting the desired result. I want to give structure to the list. As a tree or something similar.

I would take two passes at this to reshape your data into the hierarchy. I think that is the simplest thing to follow. In practice, I would probably do this in one pass, but let's do it in two for additional clarity.

Given:

titles = [
    "13.3. Risk",
    "13.3.1. Strategy",
    "SubStrategy",
    "13.3.2. Token",
    "Material",
    "Impact",
    "Aling"
]

Step 1: Create a dictionary of numbered items and their direct children

results = {}
for title in titles:
    if title[0].isnumeric():
        key, name = title.split(" ")
        key = key.strip(".")
        current = results.setdefault(key, {"name": title, "children": []})
        continue
    current["children"].append(title)

This will result in a dictionary that looks like:

{
    "13.3": {
        "name": "13.3. Risk",
        "children": []
    },
    "13.3.1": {
        "name": "13.3.1. Strategy",
        "children": [
            "SubStrategy"
        ]
    },
    "13.3.2": {
        "name": "13.3.2. Token",
        "children": [
            "Material",
            "Impact",
            "Aling"
        ]
    }
}

Step 2: Now we can iterate over it and aggregate the root(s) of the tree(s ) by setting the items as children of the appropriate parent. Note that we will assume that root(s) are nodes whose parents cannot be found.

roots = []
for key, value in results.items():
    parent_key = key.rsplit(".", 1)[0]
    if parent_key not in results:
        roots.append(value)
        continue
    results[parent_key]["children"].append(value)

Now we can use our root(s):

for root in roots:
    print("----------------------")
    print(json.dumps(root, indent=4))
    print("----------------------")

Giving us:

----------------------
{
    "name": "13.3. Risk",
    "children": [
        {
            "name": "13.3.1. Strategy",
            "children": [
                "SubStrategy"
            ]
        },
        {
            "name": "13.3.2. Token",
            "children": [
                "Material",
                "Impact",
                "Aling"
            ]
        }
    ]
}
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