[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify the code snippets into categories from the provided list of categories. List of categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']"}, {'role': 'user', 'content': "Identify to which category the provided code belongs and assign the code snippet to at least 1 but up to 5 categories based on the probabilities, ignore if the probability of the category is negligible. Strictly provide your response as a list. Avoid providing any additional information, commentary, or personal opinions.\\nPython Code:#DATA preporcessing\n\n#standardizing\nstd_scale = preprocessing.StandardScaler().fit(train)\ntrain_std = std_scale.transform(train)\ntest_std = std_scale.transform(test)\n\n\n# #PCA\n# pca_std = PCA(n_components=10).fit(train_std)\n# train_stdwPCA = pca_std.transform(train_std)\n# test_stdwPCA = pca_std.transform(test_std)\n\n#normalize\ntrain_normalized = preprocessing.normalize(train_std, norm='l2')\ntest_normalized = preprocessing.normalize(test_std, norm='l2')\n\n\n"}, {'role': 'assistant', 'content': "['data_preprocessing']"}]