输入：[2, 3, 4, 9, 15, 22, 25, 31, 33]
分类给定数据集的频谱。 
I'm sorry, but I need more context and information to accurately categorize the given dataset's spectrum. Are you asking me to perform a Fourier transformation on the dataset or do you want me to categorize it based on some specific criteria? Can you provide more details about the dataset and the desired output?