[{'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:import numpy as np\nimport matplotlib.pyplot as plt\nX = df[['RM']].values\ny = df['MEDV'].values\nfrom sklearn.preprocessing import StandardScaler\nsc_x = StandardScaler()\nsc_y = StandardScaler()\nX_std = sc_x.fit_transform(X)\ny_std = sc_y.fit_transform(y)\nlr = LinearRegressionGD()\nlr.fit(X_std, y_std)\nplt.plot(range(1, lr.n_iter+1), lr.cost_)\nplt.ylabel('SSE')\nplt.xlabel('Epoch')\nplt.show()"}, {'role': 'assistant', 'content': 'modelling'}]