[{'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:# Train & Test split\nfrom sklearn.model_selection import train_test_split\nX=data_merged.drop(['Date','Sales'],axis=1)\ny=np.log(data_merged['Sales']+1)\ntrain_x,validate_x,train_y,validate_y = train_test_split(X,y,test_size=0.20,random_state=1)\ntrain_x.shape,validate_x.shape,train_y.shape,validate_y.shape"}, {'role': 'assistant', 'content': 'data_preprocessing'}]