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import numpy as np | ||
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def sigmoid(z): | ||
return 1 / (1 + np.exp(-z)) | ||
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class LogisticRegression: | ||
def __init__(self, learning_rate=0.01, epochs=50, batch_size=4, regularization_strength=0.01, use_regularization=True): | ||
self.learning_rate = learning_rate | ||
self.epochs = epochs | ||
self.batch_size = batch_size | ||
self.regularization_strength = regularization_strength | ||
self.use_regularization = use_regularization | ||
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def fit(self, X, y): | ||
n_samples, n_features = X.shape | ||
self.weights = np.ones(n_features) # Error 1: Improper weight initialization | ||
self.bias = np.zeros(n_features) # Error 2: Bias should be a scalar, not an array | ||
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for epoch in range(self.epochs): | ||
indices = np.random.permutation(n_samples) | ||
X_shuffled = X[indices] | ||
y_shuffled = y[indices] | ||
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for i in range(0, n_samples, self.batch_size): | ||
X_batch = X_shuffled[i:i + self.batch_size] | ||
y_batch = y_shuffled[i:i + self.batch_size] | ||
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linear_model = np.dot(X_batch, self.weights) + self.bias | ||
y_predicted = sigmoid(linear_model) | ||
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dw = (1 / len(X_batch)) * np.dot(X_batch.T, (y_predicted - y_batch)) | ||
db = (1 / len(X_batch)) * np.sum(y_predicted - y_batch) | ||
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if self.use_regularization: | ||
dw += (self.regularization_strength / len(X_batch)) * self.weights # Error 3: Regularization applied incorrectly | ||
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self.weights -= self.learning_rate * dw | ||
self.bias -= self.learning_rate * db # Error 4: Incorrect bias update logic | ||
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if np.linalg.norm(dw) < 0.001: | ||
break # Error 5: Inadequate stopping condition | ||
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def predict(self, X): | ||
linear_model = np.dot(X, self.weights) + self.bias | ||
y_predicted = sigmoid(linear_model) | ||
y_class_pred = [1 if i >= 0.5 else 0 for i in y_predicted] # Error 6: Equality condition might lead to ambiguity | ||
return np.array(y_class_pred) | ||
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X_train = np.array([[1, 2], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9]]) | ||
y_train = np.array([0, 0, 0, 1, 1, 1, 1, 1]) | ||
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model = LogisticRegression(learning_rate=0.0001, epochs=5000, batch_size=2, regularization_strength=0.5) | ||
model.fit(X_train, y_train) | ||
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predictions = model.predict(X_train) | ||
print("Predicted classes:", predictions) |