一直在思考在对数据进行处理时，对数化比如 log2或者是log10处理的目的，感觉下面的说法很有道理：
Log transformation is just one way to make the skewed distribution less skewed. For parametric statistical methods,
it helps to satisfy the assumption of inferential statistics. For non-parametric methods, it does not matter if the data
is skewed or not. Log is not the only way to make the transformation, box-cox method could help you find the best
transformation for your data. however log is indeed the most powerful one.