Add average operator (and other statistical)

[mincequi]

Hi @victimsnino
i am opening another thread, since it might exceed my original request(s) a bit...

How open are you about non-(rx)-standard filters?

The average operator is already part of the original rx definition (which i also have a usage for).
However, other filters come to my mind like exponential moving average or median filtering. Those are realised in influxdb:
https://docs.influxdata.com/flux/v0.x/stdlib/universe/exponentialmovingaverage/
https://docs.influxdata.com/flux/v0.x/stdlib/universe/median/

I don't know, whether there are implementations for other languages, but those filters would be pretty helpful for financial, statistical and signal processing applications (and for my application...).

Looking forward to your opinion on that.

[AlexInLog]

Hi @mincequi,
of course i would implement average operator. Most probably to do it i would need to implement reduce operator. As a result, it would be possible for any user to create their own operators based on reduce operator with help of providing only one callable/lambda to show "how to calculate what i want". So, it would be possible to implement it by this way.

I'm not sure that I'm ready to implement all of this statistical functions by my own, but you can create PRs for each of them after I implement reduce and if no any issues in your PR i would be glad to merge it :-)

[mincequi]

That sounds good to me. Could be a good exercise for me to implement those operators :-)

[AlexInLog]

@mincequi, implemented! =)