[{'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:#categorical columns change to one-hot encoding data\n\ndef replaced_with_onehot_cols(data: DataFrame, col_names: List[str]) -> DataFrame:\n    data = data.copy()\n    \n    for col_name in col_names:\n        one_hot = pd.get_dummies(data[col_name], prefix=col_name)\n        data = data.join(one_hot)\n        \n        # Original column is not needed anymore\n        del data[col_name]\n    return data'}, {'role': 'assistant', 'content': 'data_preprocessing'}]