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"""Annif backend using the Omikuji classifier""" |
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from __future__ import annotations |
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import os.path |
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import shutil |
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from typing import TYPE_CHECKING, Any |
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import omikuji |
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import annif.util |
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from annif.exception import ( |
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NotInitializedException, |
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NotSupportedException, |
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OperationFailedException, |
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) |
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from annif.suggestion import SubjectSuggestion, SuggestionBatch |
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from . import backend, mixins |
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if TYPE_CHECKING: |
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from scipy.sparse._csr import csr_matrix |
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from annif.corpus.document import DocumentCorpus |
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class OmikujiBackend(mixins.TfidfVectorizerMixin, backend.AnnifBackend): |
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"""Omikuji based backend for Annif""" |
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name = "omikuji" |
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# defaults for uninitialized instances |
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_model = None |
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TRAIN_FILE = "omikuji-train.txt" |
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MODEL_FILE = "omikuji-model" |
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DEFAULT_PARAMETERS = { |
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"min_df": 1, |
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"ngram": 1, |
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"cluster_balanced": True, |
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"cluster_k": 2, |
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"max_depth": 20, |
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"collapse_every_n_layers": 0, |
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} |
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def _initialize_model(self) -> None: |
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if self._model is None: |
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path = os.path.join(self.datadir, self.MODEL_FILE) |
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self.debug("loading model from {}".format(path)) |
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if os.path.exists(path): |
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try: |
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self._model = omikuji.Model.load(path) |
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except RuntimeError: |
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raise OperationFailedException( |
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"Omikuji models trained on Annif versions older than " |
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"0.56 cannot be loaded. Please retrain your project." |
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) |
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else: |
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raise NotInitializedException( |
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"model {} not found".format(path), backend_id=self.backend_id |
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) |
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def initialize(self, parallel: bool = False) -> None: |
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self.initialize_vectorizer() |
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self._initialize_model() |
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def _create_train_file(self, veccorpus: csr_matrix, corpus: DocumentCorpus) -> None: |
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self.info("creating train file") |
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path = os.path.join(self.datadir, self.TRAIN_FILE) |
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with open(path, "w", encoding="utf-8") as trainfile: |
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# Extreme Classification Repository format header line |
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# We don't yet know the number of samples, as some may be skipped |
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print( |
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"00000000", |
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len(self.vectorizer.vocabulary_), |
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len(self.project.subjects), |
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file=trainfile, |
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) |
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n_samples = 0 |
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for doc, vector in zip(corpus.documents, veccorpus): |
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subject_ids = [str(subject_id) for subject_id in doc.subject_set] |
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feature_values = [ |
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"{}:{}".format(col, vector[row, col]) |
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for row, col in zip(*vector.nonzero()) |
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] |
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if not subject_ids or not feature_values: |
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continue # noqa |
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print(",".join(subject_ids), " ".join(feature_values), file=trainfile) |
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n_samples += 1 |
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# replace the number of samples value at the beginning |
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trainfile.seek(0) |
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print("{:08d}".format(n_samples), end="", file=trainfile) |
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def _create_model(self, params: dict[str, Any], jobs: int) -> None: |
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train_path = os.path.join(self.datadir, self.TRAIN_FILE) |
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model_path = os.path.join(self.datadir, self.MODEL_FILE) |
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hyper_param = omikuji.Model.default_hyper_param() |
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hyper_param.cluster_balanced = annif.util.boolean(params["cluster_balanced"]) |
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hyper_param.cluster_k = int(params["cluster_k"]) |
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hyper_param.max_depth = int(params["max_depth"]) |
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hyper_param.collapse_every_n_layers = int(params["collapse_every_n_layers"]) |
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self._model = omikuji.Model.train_on_data(train_path, hyper_param, jobs or None) |
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if os.path.exists(model_path): |
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shutil.rmtree(model_path) |
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self._model.save(os.path.join(self.datadir, self.MODEL_FILE)) |
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def _train( |
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self, |
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corpus: DocumentCorpus, |
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params: dict[str, Any], |
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jobs: int = 0, |
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) -> None: |
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if corpus != "cached": |
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if corpus.is_empty(): |
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raise NotSupportedException( |
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"Cannot train omikuji project with no documents" |
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) |
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input = (doc.text for doc in corpus.documents) |
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vecparams = { |
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"min_df": int(params["min_df"]), |
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"tokenizer": self.project.analyzer.tokenize_words, |
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"ngram_range": (1, int(params["ngram"])), |
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} |
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veccorpus = self.create_vectorizer(input, vecparams) |
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self._create_train_file(veccorpus, corpus) |
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else: |
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self.info("Reusing cached training data from previous run.") |
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self._create_model(params, jobs) |
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def _suggest_batch( |
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self, texts: list[str], params: dict[str, Any] |
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) -> SuggestionBatch: |
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vector = self.vectorizer.transform(texts) |
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limit = int(params["limit"]) |
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batch_results = [] |
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for row in vector: |
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if row.nnz == 0: # All zero vector, empty result |
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batch_results.append([]) |
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continue |
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feature_values = [(col, row[0, col]) for col in row.nonzero()[1]] |
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results = [] |
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for subj_id, score in self._model.predict(feature_values, top_k=limit): |
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results.append(SubjectSuggestion(subject_id=subj_id, score=score)) |
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batch_results.append(results) |
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return SuggestionBatch.from_sequence(batch_results, self.project.subjects) |
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