DRILL crashes from time to time when training on randomly generated learning problems

[MichaelRoeder]

Problem

DRILL crashes sometimes during its training phase because of an assertion that is not fulfilled.

Goal Concept:    Q154797        E^+:[3]  E^-:[3]
Traceback (most recent call last):
  File "/local/upb/users/q/quannian/profiles/unix/cs/Pycharm_Project/Ontolearn-0.7.3/Ontolearn/examples/concept_learning_drill_train.py", line 125, in <module>
    start(parser.parse_args())
  File "/local/upb/users/q/quannian/profiles/unix/cs/Pycharm_Project/Ontolearn-0.7.3/Ontolearn/examples/concept_learning_drill_train.py", line 50, in start
    drill.train(num_of_target_concepts=args.num_of_target_concepts,
  File "/upb/users/q/quannian/profiles/unix/cs/.conda/envs/ontolearn-0.7.3/lib/python3.10/site-packages/ontolearn/learners/drill.py", line 263, in train
    sum_of_rewards_per_actions = self.rl_learning_loop(pos_uri=frozenset(positives),
  File "/upb/users/q/quannian/profiles/unix/cs/.conda/envs/ontolearn-0.7.3/lib/python3.10/site-packages/ontolearn/learners/drill.py", line 224, in rl_learning_loop
    sequence_of_states, rewards = self.sequence_of_actions(root_rl_state)
  File "/upb/users/q/quannian/profiles/unix/cs/.conda/envs/ontolearn-0.7.3/lib/python3.10/site-packages/ontolearn/learners/drill.py", line 458, in sequence_of_actions
    assert current_state.quality > 0
AssertionError

How to recreate

import json
from argparse import ArgumentParser
from ontolearn.triple_store import TripleStoreKnowledgeBase
from ontolearn.triple_store import TripleStore
import numpy as np
from sklearn.model_selection import StratifiedKFold
from ontolearn.utils.static_funcs import compute_f1_score
from ontolearn.knowledge_base import KnowledgeBase
from ontolearn.learning_problem import PosNegLPStandard
from ontolearn.refinement_operators import LengthBasedRefinement
from ontolearn.learners import Drill
from ontolearn.metrics import F1
from ontolearn.heuristics import CeloeBasedReward
from owlapy.owl_individual import OWLNamedIndividual, IRI
from owlapy.render import DLSyntaxObjectRenderer


def start(args):
    kb = TripleStoreKnowledgeBase('http://dice-quan.cs.uni-paderborn.de:9080/sparql')
    drill = Drill(knowledge_base=kb,
                  path_embeddings=args.path_embeddings,
                  refinement_operator=LengthBasedRefinement(knowledge_base=kb),
                  quality_func=F1(),
                  reward_func=CeloeBasedReward(),
                  epsilon_decay=args.epsilon_decay,
                  learning_rate=args.learning_rate,
                  num_of_sequential_actions=args.num_of_sequential_actions,
                  num_episode=args.num_episode,
                  iter_bound=args.iter_bound,
                  max_runtime=args.max_runtime)
    if args.path_pretrained_dir:
        drill.load(directory=args.path_pretrained_dir)
    else:
        drill.train(num_of_target_concepts=args.num_of_target_concepts,
                    num_learning_problems=args.num_of_training_learning_problems)
        drill.save(directory="pretrained_drill")

    with open(args.path_learning_problem) as json_file:
        examples = json.load(json_file)
        print(examples)
    p = examples['positive_examples']
    n = examples['negative_examples']
    kf = StratifiedKFold(n_splits=args.folds, shuffle=True, random_state=args.random_seed)
    X = np.array(p + n)
    Y = np.array([1.0 for _ in p] + [0.0 for _ in n])
    dl_render = DLSyntaxObjectRenderer()
    for (ith, (train_index, test_index)) in enumerate(kf.split(X, Y)):
        train_pos = {pos_individual for pos_individual in X[train_index][Y[train_index] == 1]}
        train_neg = {neg_individual for neg_individual in X[train_index][Y[train_index] == 0]}
        test_pos = {pos_individual for pos_individual in X[test_index][Y[test_index] == 1]}
        test_neg = {neg_individual for neg_individual in X[test_index][Y[test_index] == 0]}
        train_lp = PosNegLPStandard(pos=set(map(OWLNamedIndividual, map(IRI.create, train_pos))),
                                    neg=set(map(OWLNamedIndividual, map(IRI.create, train_neg))))

        test_lp = PosNegLPStandard(pos=set(map(OWLNamedIndividual, map(IRI.create, test_pos))),
                                   neg=set(map(OWLNamedIndividual, map(IRI.create, test_neg))))

        pred_drill = drill.fit(train_lp).best_hypotheses()
        train_f1_drill = compute_f1_score(individuals=frozenset({i for i in kb.individuals(pred_drill)}),
                                          pos=train_lp.pos,
                                          neg=train_lp.neg)
        # () Quality on test data
        test_f1_drill = compute_f1_score(individuals=frozenset({i for i in kb.individuals(pred_drill)}),
                                         pos=test_lp.pos,
                                         neg=test_lp.neg)
        print(
            f"Prediction: {dl_render.render(pred_drill)} | Train Quality: {train_f1_drill:.3f} | Test Quality: {test_f1_drill:.3f} \n")


if __name__ == '__main__':
    parser = ArgumentParser()
    # General
    parser.add_argument("--path_knowledge_base", type=str,
                        default="http://dice-quan.cs.uni-paderborn.de:9080/sparql")
    parser.add_argument("--path_embeddings", type=str,
                        default='/upb/users/q/quannian/profiles/unix/cs/Pycharm_Project/Dice-Embeddings-CSV/QALD10/2024-09-25 13-44-09.306901/Embedding/Removed_Keci_entity_embeddings.csv')
    parser.add_argument("--num_of_target_concepts",
                        type=int,
                        default=1)
    parser.add_argument("--num_of_training_learning_problems",
                        type=int,
                        default=1)
    parser.add_argument("--path_pretrained_dir", type=str, default=None)

    parser.add_argument("--path_learning_problem", type=str, default='/upb/users/q/quannian/profiles/unix/cs/Pycharm_Project/Dice-Embeddings-CSV/QALD10/TandF_MST5_Drill.json',
                        help="Path to a .json file that contains 2 properties 'positive_examples' and "
                             "'negative_examples'. Each of this properties should contain the IRIs of the respective"
                             "instances. e.g. 'some/path/lp.json'")
    parser.add_argument("--max_runtime", type=int, default=1, help="Max runtime")
    parser.add_argument("--folds", type=int, default=10, help="Number of folds of cross validation.")
    parser.add_argument("--random_seed", type=int, default=1)
    parser.add_argument("--iter_bound", type=int, default=10_000, help='iter_bound during testing.')
    # DQL related
    parser.add_argument("--num_episode", type=int, default=1, help='Number of trajectories created for a given lp.')

    parser.add_argument("--epsilon_decay", type=float, default=.01, help='Epsilon greedy trade off per epoch')
    parser.add_argument("--max_len_replay_memory", type=int, default=1024,
                        help='Maximum size of the experience replay')
    parser.add_argument("--num_epochs_per_replay", type=int, default=2,
                        help='Number of epochs on experience replay memory')
    parser.add_argument('--num_of_sequential_actions', type=int, default=1, help='Length of the trajectory.')

    # NN related
    parser.add_argument("--learning_rate", type=int, default=.01)

    start(parser.parse_args())```

Please message Quan if you need the embedding file or any other additional information.

[Demirrr]

The issue stems from the fact that for the sampled learning problem, the root state (Top concept) has zero quality.
For a given E^+:[3] E^-:[3], Quality(T,E+, E-) must be strictly greater than 0. Yet, on that particular dataset, and the learning problem, this is not satisfied.

[Demirrr]

Thank you. I will improve the assertion error message to ensure that the reason behind this error is clear

[MichaelRoeder]

I understand that the top concept shouldn't have a quality of zero. That is clearly a problem. So I guess this means that we should check in detail why the scoring method returns a quality of zero although the algorithm was able to select positive and negative examples beforehand, right? 🤔

[Demirrr]

the algorithm was able to select positive and negative examples beforehand, right?

The error might stem from the fact after sampling positive and negative examples, we do not ensure that the sampled sets are different form each other, e.g.,

lp = (str_dl_concept_i,set(random.sample(individuals_i, size_of_examples)),set(random.sample(individuals_j, size_of_examples)))

here