Issue #18057 has been updated by mrkn (Kenta Murata).


I created [enumerable-statistics gem](https://github.com/mrkn/enumerable-statistics) to provide the methods for calculating precise statistical summary in Array and Enumerable.  Does this gem fit your use cases?

I think this is unnecessary to provide in the core because average values can be calculated by `ary.sum / ary.length` without floating-point arithmetic errors.  If we provide this method in the core, why not provide `stddev` or `variance`, which need complex calculations to avoid floating-point arithmetic errors.

If this feature request will be accepted by any chance, I prefer `mean` over `average` because in many languages, such a functions are named `mean` instead of `average`.  For example Python's `statistics.mean`, pandas's `pandas.Series.mean`, NumPy's `numpy.mean`, Julia's `Statistics.mean`, Boost's `<boost/accumulators/statistics/mean.hpp>`, etc.


----------------------------------------
Feature #18057: Introduce Array#average
https://bugs.ruby-lang.org/issues/18057#change-93084

* Author: ggmichaelgo (Michael Go)
* Status: Open
* Priority: Normal
----------------------------------------
Introduce Array#average to calculate the average value of an array.

```ruby
array = [1, 2, 3]
array.average # 2

array = [1.5, 2.2, 3.1]
array.average(&:round) # 2

array = [-3, -2, -1]
array.average { |e| e.abs } # 2
```



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