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"""Representing suggested subjects.""" |
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import abc |
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import collections |
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import itertools |
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import numpy as np |
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from scipy.sparse import csr_array, dok_array |
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SubjectSuggestion = collections.namedtuple("SubjectSuggestion", "subject_id score") |
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WeightedSuggestionsBatch = collections.namedtuple( |
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"WeightedSuggestionsBatch", "hit_sets weight subjects" |
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) |
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class SuggestionFilter: |
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"""A reusable filter for filtering SubjectSuggestion objects.""" |
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def __init__(self, subject_index, limit=None, threshold=0.0): |
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self._subject_index = subject_index |
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self._limit = limit |
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self._threshold = threshold |
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def __call__(self, orighits): |
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return LazySuggestionResult( |
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lambda: orighits.filter(self._subject_index, self._limit, self._threshold) |
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) |
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class SuggestionResult(metaclass=abc.ABCMeta): |
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"""Abstract base class for a set of hits returned by an analysis |
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operation.""" |
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@abc.abstractmethod |
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def as_list(self): |
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"""Return the hits as an ordered sequence of SubjectSuggestion objects, |
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highest scores first.""" |
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pass # pragma: no cover |
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@abc.abstractmethod |
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def as_vector(self, size, destination=None): |
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"""Return the hits as a one-dimensional score vector of given size. |
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If destination array is given (not None) it will be used, otherwise a |
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new array will be created.""" |
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pass # pragma: no cover |
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@abc.abstractmethod |
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def filter(self, subject_index, limit=None, threshold=0.0): |
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"""Return a subset of the hits, filtered by the given limit and |
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score threshold, as another SuggestionResult object.""" |
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pass # pragma: no cover |
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@abc.abstractmethod |
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def __len__(self): |
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"""Return the number of hits with non-zero scores.""" |
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pass # pragma: no cover |
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class LazySuggestionResult(SuggestionResult): |
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"""SuggestionResult implementation that wraps another SuggestionResult which |
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is initialized lazily only when it is actually accessed. Method calls |
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will be proxied to the wrapped SuggestionResult.""" |
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def __init__(self, construct): |
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"""Create the proxy object. The given construct function will be |
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called to create the actual SuggestionResult when it is needed.""" |
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self._construct = construct |
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self._object = None |
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def _initialize(self): |
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if self._object is None: |
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self._object = self._construct() |
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def as_list(self): |
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self._initialize() |
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return self._object.as_list() |
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def as_vector(self, size, destination=None): |
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self._initialize() |
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return self._object.as_vector(size, destination) |
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def filter(self, subject_index, limit=None, threshold=0.0): |
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self._initialize() |
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return self._object.filter(subject_index, limit, threshold) |
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def __len__(self): |
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self._initialize() |
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return len(self._object) |
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class VectorSuggestionResult(SuggestionResult): |
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"""SuggestionResult implementation based primarily on NumPy vectors.""" |
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def __init__(self, vector): |
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vector_f32 = vector.astype(np.float32) |
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# limit scores to the range 0.0 .. 1.0 |
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self._vector = np.minimum(np.maximum(vector_f32, 0.0), 1.0) |
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self._subject_order = None |
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self._lsr = None |
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def _vector_to_list_suggestion(self): |
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hits = [] |
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for subject_id in self.subject_order: |
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score = self._vector[subject_id] |
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if score <= 0.0: |
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break # we can skip the remaining ones |
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hits.append(SubjectSuggestion(subject_id=subject_id, score=float(score))) |
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return ListSuggestionResult(hits) |
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@property |
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def subject_order(self): |
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if self._subject_order is None: |
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self._subject_order = np.argsort(self._vector)[::-1] |
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return self._subject_order |
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def as_list(self): |
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if self._lsr is None: |
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self._lsr = self._vector_to_list_suggestion() |
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return self._lsr.as_list() |
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def as_vector(self, size, destination=None): |
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if destination is not None: |
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np.copyto(destination, self._vector) |
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return destination |
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return self._vector |
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def filter(self, subject_index, limit=None, threshold=0.0): |
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mask = self._vector > threshold |
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deprecated_ids = subject_index.deprecated_ids() |
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if limit is not None: |
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limit_mask = np.zeros_like(self._vector, dtype=bool) |
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deprecated_set = set(deprecated_ids) |
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top_k_subjects = itertools.islice( |
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(subj for subj in self.subject_order if subj not in deprecated_set), |
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limit, |
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) |
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limit_mask[list(top_k_subjects)] = True |
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mask = mask & limit_mask |
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else: |
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deprecated_mask = np.ones_like(self._vector, dtype=bool) |
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deprecated_mask[deprecated_ids] = False |
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mask = mask & deprecated_mask |
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vsr = VectorSuggestionResult(self._vector * mask) |
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return ListSuggestionResult(vsr.as_list()) |
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def __len__(self): |
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return (self._vector > 0.0).sum() |
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class ListSuggestionResult(SuggestionResult): |
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"""SuggestionResult implementation based primarily on lists of hits.""" |
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def __init__(self, hits): |
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self._list = [self._enforce_score_range(hit) for hit in hits if hit.score > 0.0] |
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self._vector = None |
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@staticmethod |
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def _enforce_score_range(hit): |
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if hit.score > 1.0: |
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return hit._replace(score=1.0) |
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return hit |
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def _list_to_vector(self, size, destination): |
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if destination is None: |
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destination = np.zeros(size, dtype=np.float32) |
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for hit in self._list: |
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if hit.subject_id is not None: |
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destination[hit.subject_id] = hit.score |
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return destination |
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def as_list(self): |
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return self._list |
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def as_vector(self, size, destination=None): |
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if self._vector is None: |
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self._vector = self._list_to_vector(size, destination) |
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return self._vector |
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def filter(self, subject_index, limit=None, threshold=0.0): |
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hits = sorted(self._list, key=lambda hit: hit.score, reverse=True) |
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filtered_hits = [ |
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hit |
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for hit in hits |
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if hit.score >= threshold and hit.score > 0.0 and hit.subject_id is not None |
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] |
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if limit is not None: |
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filtered_hits = filtered_hits[:limit] |
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return ListSuggestionResult(filtered_hits) |
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def __len__(self): |
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return len(self._list) |
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class SparseSuggestionResult(SuggestionResult): |
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"""SuggestionResult implementation backed by a single row of a sparse array.""" |
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def __init__(self, array, idx): |
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self._array = array |
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self._idx = idx |
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def as_list(self): |
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_, cols = self._array[[self._idx], :].nonzero() |
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suggestions = [ |
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SubjectSuggestion(subject_id=col, score=float(self._array[self._idx, col])) |
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for col in cols |
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] |
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return sorted( |
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suggestions, key=lambda suggestion: suggestion.score, reverse=True |
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) |
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def as_vector(self, size, destination=None): |
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if destination is not None: |
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print("as_vector called with destination not None") |
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return None |
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return self._array[[self._idx], :].toarray()[0] |
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def filter(self, subject_index, limit=None, threshold=0.0): |
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lsr = ListSuggestionResult(self.as_list()) |
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return lsr.filter(subject_index, limit, threshold) |
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def __len__(self): |
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_, cols = self._array[[self._idx], :].nonzero() |
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return len(cols) |
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class SuggestionBatch: |
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"""Subject suggestions for a batch of documents.""" |
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def __init__(self, array): |
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"""Create a new SuggestionBatch from a csr_array""" |
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self.array = array |
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@classmethod |
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def from_sequence(cls, suggestion_results, vocab_size): |
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"""Create a new SuggestionBatch from a sequence of SuggestionResult objects.""" |
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# create a dok_array for fast construction |
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ar = dok_array((len(suggestion_results), vocab_size), dtype=np.float32) |
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for idx, result in enumerate(suggestion_results): |
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for suggestion in result.as_list(): |
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ar[idx, suggestion.subject_id] = suggestion.score |
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return cls(ar.tocsr()) |
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def filter(self, subject_index, limit=None, threshold=0.0): |
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"""Return a subset of the hits, filtered by the given limit and |
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score threshold, as another SuggestionBatch object.""" |
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from annif.util import filter_suggestion |
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return SuggestionBatch(filter_suggestion(self.array, limit, threshold)) |
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def __getitem__(self, idx): |
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if idx < 0 or idx >= len(self): |
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raise IndexError |
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return SparseSuggestionResult(self.array, idx) |
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def __len__(self): |
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return self.array.shape[0] |
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