50 lines
1.9 KiB
Python
50 lines
1.9 KiB
Python
from typing import Mapping, List, Union, Tuple
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import numpy as np
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from PIL.Image import Image
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from image_prediction.estimator.adapter.adapter import EstimatorAdapter
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from image_prediction.exceptions import UnexpectedPredictionFormat
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from image_prediction.utils import get_logger
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logger = get_logger()
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class Classifier:
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def __init__(self, estimator_adapter: EstimatorAdapter, classes: Mapping[int, str]):
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"""Abstraction layer over different estimator backends (e.g. keras or scikit-learn). For each backend to be used
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an EstimatorAdapter must be implemented.
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Args:
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estimator_adapter: adapter for a given estimator backend; expected to be a classifier that returns mappings
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from numeric labels to probabilities as predictions or numeric labels
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classes: mapping from a numerical label to a human-readable label for classes
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"""
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self.__estimator_adapter = estimator_adapter
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self._classes = classes
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def __validate_prediction_format(self, prediction):
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if not max(prediction.keys) <= len(self._classes):
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raise UnexpectedPredictionFormat(f"Received prediction in an unexpected format: {prediction}")
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def __format_prediction(self, prediction):
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if isinstance(prediction, int):
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return self._classes[prediction]
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elif isinstance(prediction, dict):
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self.__validate_prediction_format(prediction)
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return {self._classes[cls_idx] for cls_idx, prob in prediction.items()}
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else:
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return prediction
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def predict(self, batch: Union[np.array, Tuple[Image]]) -> List[str]:
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if not isinstance(batch, tuple) and batch.shape[0] == 0:
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return []
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return list(map(self.__format_prediction, self.__estimator_adapter.predict(batch)))
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def __call__(self, batch: np.array) -> List[str]:
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return self.predict(batch)
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