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drc-ners-nlp/research/models/cnn_model.py
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Python

from typing import Any
import numpy as np
import pandas as pd
from tensorflow.keras.layers import (
Embedding,
Conv1D,
MaxPooling1D,
GlobalMaxPooling1D,
Dense,
Dropout,
)
from tensorflow.keras.models import Sequential
from research.neural_network_model import NeuralNetworkModel
class CNNModel(NeuralNetworkModel):
"""1D Convolutional Neural Network for character patterns"""
def build_model_with_vocab(self, vocab_size: int, max_len: int = 20, **kwargs) -> Any:
"""Build CNN model with known vocabulary size"""
params = kwargs
model = Sequential(
[
Embedding(input_dim=vocab_size, output_dim=params.get("embedding_dim", 64)),
Conv1D(
filters=params.get("filters", 64),
kernel_size=params.get("kernel_size", 3),
activation="relu",
),
MaxPooling1D(pool_size=2),
Conv1D(
filters=params.get("filters", 64),
kernel_size=params.get("kernel_size", 3),
activation="relu",
),
GlobalMaxPooling1D(),
Dense(64, activation="relu"),
Dropout(params.get("dropout", 0.5)),
Dense(2, activation="softmax"),
]
)
model.compile(
loss="sparse_categorical_crossentropy", optimizer="adam", metrics=["accuracy"]
)
return model
def prepare_features(self, X: pd.DataFrame) -> np.ndarray:
"""Prepare sequences for CNN using extracted features"""
# X here contains the features already extracted by FeatureExtractor
from tensorflow.keras.preprocessing.text import Tokenizer
from tensorflow.keras.preprocessing.sequence import pad_sequences
# Get text data from extracted features - use character level for CNN
text_data = []
for feature_type in self.config.features:
if feature_type.value in X.columns:
text_data.extend(X[feature_type.value].astype(str).tolist())
if not text_data:
# Fallback - should not happen if FeatureExtractor is properly configured
text_data = [""] * len(X)
# Initialize character-level tokenizer
if self.tokenizer is None:
self.tokenizer = Tokenizer(char_level=True, lower=True, oov_token="<OOV>")
self.tokenizer.fit_on_texts(text_data)
sequences = self.tokenizer.texts_to_sequences(text_data[: len(X)])
max_len = self.config.model_params.get("max_len", 20) # Longer for character level
return pad_sequences(sequences, maxlen=max_len, padding="post")