R：如何将移动平均值应用于数据框中的列子集？

I have a dataframe (training.set) that is 150 observations of 83 variables. I want to transform 82 of those columns with some moving averages. The problem is the results end up only being 150 numeric values (i.e. 1 column). I have a dataframe (training.set) that is 150 o