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""" |
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Goal Function for seq2sick |
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------------------------------------------------------- |
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""" |
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import functools |
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import numpy as np |
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from textattack.shared.utils import words_from_text |
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from .text_to_text_goal_function import TextToTextGoalFunction |
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class NonOverlappingOutput(TextToTextGoalFunction): |
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"""Ensures that none of the words at a position are equal. |
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Defined in seq2sick (https://arxiv.org/pdf/1803.01128.pdf), equation |
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(3). |
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""" |
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def clear_cache(self): |
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if self.use_cache: |
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self._call_model_cache.clear() |
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get_words_cached.cache_clear() |
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word_difference_score.cache_clear() |
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def _is_goal_complete(self, model_output, _): |
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return self._get_score(model_output, self.ground_truth_output) == 1.0 |
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def _get_score(self, model_output, _): |
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num_words_diff = word_difference_score(model_output, self.ground_truth_output) |
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if num_words_diff == 0: |
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return 0.0 |
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else: |
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return num_words_diff / len(get_words_cached(self.ground_truth_output)) |
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@functools.lru_cache(maxsize=2**12) |
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def get_words_cached(s): |
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return np.array(words_from_text(s)) |
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@functools.lru_cache(maxsize=2**12) |
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def word_difference_score(s1, s2): |
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"""Returns the number of words that are non-overlapping between s1 and |
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s2.""" |
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s1_words = get_words_cached(s1) |
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s2_words = get_words_cached(s2) |
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min_length = min(len(s1_words), len(s2_words)) |
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if min_length == 0: |
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return 0 |
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s1_words = s1_words[:min_length] |
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s2_words = s2_words[:min_length] |
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return (s1_words != s2_words).sum() |
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