I would do sum square. This would allow you to keep an ongoing value as an associative operation (in an aggregator) and then calculate the variance & std deviation after the fact.
On Wed, Mar 25, 2015 at 10:28 PM, Haopu Wang <hw...@qilinsoft.com> wrote: > Hi, > > > > I have a DataFrame object and I want to do types of aggregations like > count, sum, variance, stddev, etc. > > > > DataFrame has DSL to do simple aggregations like count and sum. > > > > How about variance and stddev? > > > > Thank you for any suggestions! > > >
