Sample standard deviation can't be defined in the case of N=1, because it has N-1 in the denominator. My guess is that this is the case you're seeing. A population of N=1 still has a standard deviation of course (which is 0).
On Thu, Jul 7, 2016 at 9:51 AM, Mungeol Heo <mungeol....@gmail.com> wrote: > I know stddev_samp and stddev_pop gives different values, because they > have different definition. What I want to know is why stddev_samp > gives "NaN", and not a numeric value. --------------------------------------------------------------------- To unsubscribe e-mail: user-unsubscr...@spark.apache.org
