File size: 8,505 Bytes
38593e7
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5abc469
38593e7
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
"""
Synthetic Data Generator for Drift Testing

Generates synthetic drifted datasets to test drift detection.
"""

import random
import string
from typing import List, Tuple

from loguru import logger
import numpy as np


class SyntheticDataGenerator:
    """
    Generates synthetic code comment data with controlled drift characteristics.
    """

    def __init__(self, seed: int = 42):
        """
        Initialize synthetic data generator.
        """
        self.seed = seed
        np.random.seed(seed)
        random.seed(seed)

    def generate_short_comments(
        self,
        reference_texts: List[str],
        ratio: float = 0.5,
        n_samples: int = 100,
    ) -> List[str]:
        """
        Generate shorter comments (text length drift).
        """
        short_comments = []

        for _ in range(n_samples):
            ref_text = np.random.choice(reference_texts)
            words = ref_text.split()
            truncated_len = max(1, int(len(words) * ratio))
            short_text = " ".join(words[:truncated_len])
            short_comments.append(short_text)

        logger.debug(f"Generated {len(short_comments)} short comments")
        return short_comments

    def generate_long_comments(
        self,
        reference_texts: List[str],
        ratio: float = 1.5,
        n_samples: int = 100,
    ) -> List[str]:
        """
        Generate longer comments (text length drift upward).
        """
        long_comments = []

        for _ in range(n_samples):
            ref_text = np.random.choice(reference_texts)
            words = ref_text.split()
            target_len = max(1, int(len(words) * ratio))

            extended_words = words.copy()
            while len(extended_words) < target_len:
                extended_words.append(np.random.choice(words))

            long_text = " ".join(extended_words[:target_len])
            long_comments.append(long_text)

        logger.debug(f"Generated {len(long_comments)} long comments")
        return long_comments

    def generate_corrupted_vocabulary(
        self,
        reference_texts: List[str],
        corruption_rate: float = 0.5,
        n_samples: int = 100,
    ) -> List[str]:
        """
        Generate texts with corrupted vocabulary (typos, character swaps).

        Args:
            reference_texts: Reference training texts
            corruption_rate: Fraction of words to corrupt (0.0-1.0)
            n_samples: Number of samples to generate

        Returns:
            List of corrupted texts
        """
        corrupted_texts = []

        for _ in range(n_samples):
            ref_text = np.random.choice(reference_texts)
            words = ref_text.split()

            # Corrupt some words
            for i in range(len(words)):
                if random.random() < corruption_rate:
                    word = words[i]
                    if len(word) > 2:
                        # Random character swap or substitution
                        if random.random() < 0.5:
                            # Character swap
                            idx = random.randint(0, len(word) - 2)
                            word = word[:idx] + word[idx + 1] + word[idx] + word[idx + 2 :]
                        else:
                            # Character substitution
                            idx = random.randint(0, len(word) - 1)
                            word = (
                                word[:idx]
                                + random.choice(string.ascii_lowercase)
                                + word[idx + 1 :]
                            )
                    words[i] = word

            corrupted_text = " ".join(words)
            corrupted_texts.append(corrupted_text)

        logger.debug(f"Generated {len(corrupted_texts)} corrupted texts (rate={corruption_rate})")
        return corrupted_texts

    def generate_label_shift(
        self,
        reference_texts: List[str],
        reference_labels: np.ndarray,
        shift_type: str = "class_imbalance",
        n_samples: int = 100,
    ) -> Tuple[List[str], np.ndarray]:
        """
        Generate batch with label distribution shift (class imbalance).

        Args:
            reference_texts: Reference training texts
            reference_labels: Reference training labels (binary matrix)
            shift_type: 'class_imbalance' - favor majority class
            n_samples: Number of samples to generate

        Returns:
            Tuple of (texts, shifted_labels)
        """
        texts = []
        shifted_labels = []

        if reference_labels.ndim == 2:
            # Multi-label: get the first label per sample
            label_indices = np.argmax(reference_labels, axis=1)
        else:
            label_indices = reference_labels

        # Get class distribution
        unique_labels, counts = np.unique(label_indices, return_counts=True)
        majority_class = unique_labels[np.argmax(counts)]
        minority_classes = unique_labels[unique_labels != majority_class]

        # Create imbalanced distribution: 80% majority, 20% minority
        n_majority = int(n_samples * 0.8)
        n_minority = n_samples - n_majority

        # Sample indices with bias toward majority class
        majority_indices = np.where(label_indices == majority_class)[0]
        minority_indices = np.where(np.isin(label_indices, minority_classes))[0]

        selected_indices = []
        selected_indices.extend(np.random.choice(majority_indices, size=n_majority, replace=True))
        if len(minority_indices) > 0:
            selected_indices.extend(
                np.random.choice(minority_indices, size=n_minority, replace=True)
            )

        np.random.shuffle(selected_indices)
        selected_indices = selected_indices[:n_samples]

        # Get texts and labels
        texts = [reference_texts[i] for i in selected_indices]
        shifted_labels = reference_labels[selected_indices]

        logger.debug(f"Generated {len(texts)} samples with class imbalance")
        return texts, shifted_labels

    def generate_synthetic_batch(
        self,
        reference_texts: List[str],
        reference_labels: np.ndarray,
        drift_type: str = "none",
        batch_size: int = 50,
    ) -> Tuple[List[str], np.ndarray]:
        """
        Generate a synthetic batch with specified drift.

        Args:
            reference_texts: Reference training texts
            reference_labels: Reference training labels
            drift_type: Type of drift to introduce:
                - 'none': No drift (baseline)
                - 'text_length_short': Shortened texts
                - 'text_length_long': Elongated texts
                - 'corrupted_vocab': Typos and character swaps
                - 'class_imbalance': Biased label distribution
            batch_size: Number of samples to generate

        Returns:
            Tuple of (texts, labels)
        """
        if drift_type == "none":
            indices = np.random.choice(len(reference_texts), size=batch_size, replace=True)
            texts = [reference_texts[i] for i in indices]
            labels = reference_labels[indices]

        elif drift_type == "text_length_short":
            texts = self.generate_short_comments(reference_texts, ratio=0.5, n_samples=batch_size)
            indices = np.random.choice(len(reference_labels), size=batch_size)
            labels = reference_labels[indices]

        elif drift_type == "text_length_long":
            texts = self.generate_long_comments(reference_texts, ratio=1.5, n_samples=batch_size)
            indices = np.random.choice(len(reference_labels), size=batch_size)
            labels = reference_labels[indices]

        elif drift_type == "corrupted_vocab":
            texts = self.generate_corrupted_vocabulary(
                reference_texts, corruption_rate=0.2, n_samples=batch_size
            )
            indices = np.random.choice(len(reference_labels), size=batch_size)
            labels = reference_labels[indices]

        elif drift_type == "class_imbalance":
            texts, labels = self.generate_label_shift(
                reference_texts,
                reference_labels,
                shift_type="class_imbalance",
                n_samples=batch_size,
            )

        else:
            raise ValueError(f"Unknown drift type: {drift_type}")

        logger.info(f"Generated synthetic batch: {drift_type}, size={batch_size}")
        return texts, labels