[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify code snippets into one of the following categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']."}, {'role': 'user', 'content': "Identify the single most appropriate category to which the provided code belongs. Provide your response as a single category label without any additional information, commentary, or personal opinions.\\nPython Code:X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state = 42)\nohe = OneHotEncoder(categories='auto')\ny_train_ohe = ohe.fit_transform(y_train.reshape(-1, 1))\ny_test_ohe = ohe.fit_transform(y_test.reshape(-1, 1))\ny_ohe = ohe.fit_transform(y.reshape(-1, 1))\nscaler = StandardScaler()\nX_scale = scaler.fit_transform(X.astype(float))\nX_train_scale = scaler.fit_transform(X_train.astype(float))\nX_test_scale = scaler.transform(X_test.astype(float))"}, {'role': 'assistant', 'content': 'data_preprocessing'}]