A tutorial that demonstrates numerical data structures using Python

You can easily define a tree's data structure using Python's built-in defaultdict method.

Simply put, a tree can also be a dictionary data structure
 

def tree(): return defaultdict(tree)

That's all, just one line of code.

If you continue with the following code, you need to introduce
first  

from collections import defaultdict

instance

JSON-esque

Now we create an JSON-esque nested dictionary without explicitly creating a subdictionary:
 

users = tree()
users['harold']['username'] = 'hrldcpr'
users['handler']['username'] = 'matthandlersux'

Then you can go through < code > print(json.dumps(users)) < /code > To print JSON data, the result is:
 

{"harold": {"username": "hrldcpr"}, "handler": {"username": "matthandlersux"}}

does not require an

assignment

We do not need to assign a value to create a structure:
 

taxonomy = tree()
taxonomy['Animalia']['Chordata']['Mammalia']['Carnivora']['Felidae']['Felis']['cat']
taxonomy['Animalia']['Chordata']['Mammalia']['Carnivora']['Felidae']['Panthera']['lion']
taxonomy['Animalia']['Chordata']['Mammalia']['Carnivora']['Canidae']['Canis']['dog']
taxonomy['Animalia']['Chordata']['Mammalia']['Carnivora']['Canidae']['Canis']['coyote']
taxonomy['Plantae']['Solanales']['Solanaceae']['Solanum']['tomato']
taxonomy['Plantae']['Solanales']['Solanaceae']['Solanum']['potato']
taxonomy['Plantae']['Solanales']['Convolvulaceae']['Ipomoea']['sweet potato']

To print good information, turn it into a standard dictionary object:
 

def dicts(t): return {k: dicts(t[k]) for k in t}

You can now print pprint(dicts(taxonomy)) :
 

{'Animalia': {'Chordata': {'Mammalia': {'Carnivora': {'Canidae': {'Canis': {'coyote': {},
                                      'dog': {}}},
                           'Felidae': {'Felis': {'cat': {}},
                                 'Panthera': {'lion': {}}}}}}},
 'Plantae': {'Solanales': {'Convolvulaceae': {'Ipomoea': {'sweet potato': {}}},
              'Solanaceae': {'Solanum': {'potato': {},
                           'tomato': {}}}}}}

The substructure is also treated as a dictionary object, while the leaf node is an empty dictionary object

iteration

There are interesting ways to iterate over the tree.

For example, if we parse a list of animals and add them to the taxonomy we defined earlier, we can use the following code:
 

add(taxonomy,
  'Animalia,Chordata,Mammalia,Cetacea,Balaenopteridae,Balaenoptera,blue whale'.split(','))

Simplified implementation:
 

def add(t, keys):
 for key in keys:
  t = t[key]

We still don't need to assign:
 

{'Animalia': {'Chordata': {'Mammalia': {'Carnivora': {'Canidae': {'Canis': {'coyote': {},
                                      'dog': {}}},
                           'Felidae': {'Felis': {'cat': {}},
                                 'Panthera': {'lion': {}}}},
                    'Cetacea': {'Balaenopteridae': {'Balaenoptera': {'blue whale': {}}}}}}},
 'Plantae': {'Solanales': {'Convolvulaceae': {'Ipomoea': {'sweet potato': {}}},
              'Solanaceae': {'Solanum': {'potato': {},
                           'tomato': {}}}}}}

conclusion

All of this is probably not very useful, just some interesting code.

If you like Python, think of this as fun to understand.