EvoLearner Example Broken

[heindorf]

I tried to run python concept_learning_with_evolearner.py in the latest ontolearn version (0.80). However, I get the error

Traceback (most recent call last):
  File "/home/heindorf/git/Ontolearn/examples/concept_learning_with_evolearner.py", line 61, in <module>
    model.save_best_hypothesis(n=3, path='Predictions_{0}'.format(str_target_concept))
  File "/home/heindorf/git/Ontolearn/ontolearn/base_concept_learner.py", line 383, in save_best_hypothesis
    ontology.save(IRI.create(path + '.owl'))
  File "/home/heindorf/.conda/envs/ontolearn/lib/python3.10/site-packages/owlapy/iri.py", line 89, in create
    return IRI(string[0:index], string[index:])
  File "/home/heindorf/.conda/envs/ontolearn/lib/python3.10/site-packages/owlapy/iri.py", line 20, in __call__
    _temp = super().__call__(*args, **kwargs)
  File "/home/heindorf/.conda/envs/ontolearn/lib/python3.10/site-packages/owlapy/iri.py", line 46, in __init__
    assert namespace[-1] in ("/", ":", "#"), "It should be a valid IRI based on /, :, and #"
IndexError: string index out of range

The problem seems to be in the line model.save_best_hypothesis(n=3, path='Predictions_{0}'.format(str_target_concept))

[alkidbaci]

This is related with a change in owlapy where the standard to save an ontology is by using an IRI and what the error is indicating is that Predictions_{str_target_concept} is not a valid IRI because it does not contain one of ("/", ":", "#"). Now its true that the argument name path is a bit misleading but the path should be a valid iri in string format which basically refers to the saving filename. In this case we add a "./" before the name so it will be considered a valid IRI and filepath at the same time, i.e. (./Predictions_{str_target_concept}. These changes are recent and the example is apparently not updated.
Maybe we can alter the standard a bit to be less restrictive

[heindorf]

By the way, the same issue occurs for CELOE:

Ontolearn/examples/concept_learning_with_celoe_heuristic.py

Line 76 in 35d5e59

model.save_best_hypothesis(n=3, path='Predictions_{0}'.format(str_target_concept))

[Demirrr]

Fixed with #477
We created a text for each example so that the examples will not be broken, see
https://github.com/dice-group/Ontolearn/blob/develop/tests/test_example_celoe.py
https://github.com/dice-group/Ontolearn/blob/develop/tests/test_evolearner.py