"""
Word Swap by Random Character Insertion
------------------------------------------------
"""
import numpy as np
# from textattack.shared import utils
from .word_swap import WordSwap
[docs]class WordSwapRandomCharacterInsertion(WordSwap):
"""Transforms an input by inserting a random character.
random_one (bool): Whether to return a single word with a random
character deleted. If not, returns all possible options.
skip_first_char (bool): Whether to disregard inserting as the first
character. skip_last_char (bool): Whether to disregard inserting as
the last character.
>>> from textattack.transformations import WordSwapRandomCharacterInsertion
>>> from textattack.augmentation import Augmenter
>>> transformation = WordSwapRandomCharacterInsertion()
>>> augmenter = Augmenter(transformation=transformation)
>>> s = 'I am fabulous.'
>>> augmenter.augment(s)
"""
def __init__(
self, random_one=True, skip_first_char=False, skip_last_char=False, **kwargs
):
super().__init__(**kwargs)
self.random_one = random_one
self.skip_first_char = skip_first_char
self.skip_last_char = skip_last_char
def _get_replacement_words(self, word):
"""Returns returns a list containing all possible words with 1 random
character inserted."""
if len(word) <= 1:
return []
candidate_words = []
start_idx = 1 if self.skip_first_char else 0
end_idx = (len(word) - 1) if self.skip_last_char else len(word)
if start_idx >= end_idx:
return []
if self.random_one:
i = np.random.randint(start_idx, end_idx)
candidate_word = word[:i] + self._get_random_letter() + word[i:]
candidate_words.append(candidate_word)
else:
for i in range(start_idx, end_idx):
candidate_word = word[:i] + self._get_random_letter() + word[i:]
candidate_words.append(candidate_word)
return candidate_words
@property
def deterministic(self):
return not self.random_one
[docs] def extra_repr_keys(self):
return super().extra_repr_keys() + ["random_one"]