def get_classification_accuracy(feature_matrix, sentiment, coefficients):
    scores = np.dot(feature_matrix, coefficients)
    apply_threshold = np.vectorize(lambda x: 1. if x > 0  else -1.)
    predictions = apply_threshold(scores)
    
    num_correct = (predictions == sentiment).sum()
    accuracy = num_correct / len(feature_matrix)    
    return accuracy