Fix pre-existing flake8 errors (unused imports, whitespace, bug)

- Remove unused imports: LazyLoader, numpy, typing.List, random
- Fix missing whitespace around arithmetic operators (E226)
- Fix whitespace before ']' (E202)
- Fix bug in DifferentialEvolution: best_score was never updated,
  causing all candidates to be accepted instead of only improvements

Author: yanjunqiAz

tests/test_word_embedding.py

@@ -19,7 +19,6 @@ def test_embedding_paragramcf():
 @pytest.mark.skipif(not _gensim_available, reason="gensim is not installed")
 def test_embedding_gensim():
     # download a trained word2vec model
-    from textattack.shared.utils import LazyLoader
     from textattack.shared.utils.install import TEXTATTACK_CACHE_DIR
 
     path = os.path.join(TEXTATTACK_CACHE_DIR, "test_gensim_embedding.txt")

textattack/attacker.py

@@ -92,7 +92,7 @@ def __init__(self, attack, dataset, attack_args=None):
     def _get_worklist(self, start, end, num_examples, shuffle):
         if end - start < num_examples:
             logger.warn(
-                f"Attempting to attack {num_examples} samples when only {end-start} are available."
+                f"Attempting to attack {num_examples} samples when only {end - start} are available."
             )
         candidates = list(range(start, end))
         if shuffle:

textattack/goal_functions/custom/named_entity_recognition.py

@@ -6,8 +6,6 @@
 
 import json
 
-import numpy as np
-
 from textattack.goal_function_results import NamedEntityRecognitionGoalFunctionResult
 from textattack.goal_functions import GoalFunction
 

textattack/search_methods/differential_evolution.py

@@ -1,5 +1,3 @@
-from typing import List
-
 import numpy as np
 from scipy.optimize import differential_evolution
 
@@ -60,6 +58,7 @@ def obj(perturbation_vector):
             result = self.get_goal_results([cand])[0][0]
             cur_score = -result.score
             if cur_score <= best_score:
+                best_score = cur_score
                 best_result_found = result
             return cur_score
 

textattack/trainer.py

@@ -753,7 +753,7 @@ def train(self):
 
                 if self._global_step > 0:
                     prog_bar.set_description(
-                        f"Loss {self._total_loss/self._global_step:.5f}"
+                        f"Loss {self._total_loss / self._global_step:.5f}"
                     )
 
                 # TODO: Better way to handle TB and Wandb logging
@@ -804,7 +804,7 @@ def train(self):
                 correct_predictions = (preds == targets).sum().item()
                 accuracy = correct_predictions / len(targets)
                 metric_log = {"train/train_accuracy": accuracy}
-                logger.info(f"Train accuracy: {accuracy*100:.2f}%")
+                logger.info(f"Train accuracy: {accuracy * 100:.2f}%")
             else:
                 pearson_correlation, pearson_pvalue = scipy.stats.pearsonr(
                     preds, targets
@@ -920,7 +920,7 @@ def evaluate(self):
             eval_score = accuracy
 
         if self._metric_name == "accuracy":
-            logger.info(f"Eval {self._metric_name}: {eval_score*100:.2f}%")
+            logger.info(f"Eval {self._metric_name}: {eval_score * 100:.2f}%")
         else:
             logger.info(f"Eval {self._metric_name}: {eval_score:.4f}%")
 

textattack/training_args.py

@@ -557,7 +557,7 @@ def _create_dataset_from_args(cls, args):
                 label >= 0
                 for label in train_dataset_labels_set
                 if isinstance(label, int)
-            ), f"Train dataset has negative label/s {[label for label in train_dataset_labels_set if isinstance(label,int) and label < 0 ]} which is/are not supported by pytorch.Use --filter-train-by-labels to keep suitable labels"
+            ), f"Train dataset has negative label/s {[label for label in train_dataset_labels_set if isinstance(label, int) and label < 0]} which is/are not supported by pytorch. Use --filter-train-by-labels to keep suitable labels"
 
             assert num_labels >= len(
                 train_dataset_labels_set
@@ -569,7 +569,7 @@ def _create_dataset_from_args(cls, args):
                 label >= 0
                 for label in eval_dataset_labels_set
                 if isinstance(label, int)
-            ), f"Eval dataset has negative label/s {[label for label in eval_dataset_labels_set if isinstance(label,int) and label < 0 ]} which is/are not supported by pytorch.Use --filter-eval-by-labels to keep suitable labels"
+            ), f"Eval dataset has negative label/s {[label for label in eval_dataset_labels_set if isinstance(label, int) and label < 0]} which is/are not supported by pytorch. Use --filter-eval-by-labels to keep suitable labels"
 
             assert num_labels >= len(
                 set(eval_dataset_labels_set)

textattack/transformations/word_swaps/word_swap_differential_evolution.py

@@ -1,9 +1,9 @@
 """
 Word Swap for Differential Evolution
 -------------------------------------
-Extends WordSwap. 
+Extends WordSwap.
 
-If a Transformation wants to be compatible with 
+If a Transformation wants to be compatible with
 textattack.search_methods.DifferentialEvolution,
 then it must extend from this class.
 """

textattack/transformations/word_swaps/word_swap_invisible_characters.py

@@ -3,7 +3,6 @@
 -----------------------------------
 """
 
-import random
 from typing import List, Tuple
 
 import numpy as np