> On 12 Apr 2020, at 13:53, Cédrick Béler <cdric...@gmail.com> wrote:
>
> Beautiful ^^
I also like it.
But why the single letter variable names ? Why not:
SequenceableCollection>>#runningMeans: width
| means sum index |
means := Array new: self size - width + 1.
sum := 0.
1 to: width do: [ :each |
sum := sum + (self at: each) ].
index := 1.
means at: index put: sum / width.
width + 1 to: self size do: [ :each |
sum := sum - (self at: index) + (self at: each).
index := index + 1.
means at: index put: sum / width ].
^ means
A good comment, a correct initial bounds check and unit tests are also needed.
> I would vote for inclusion in the base image ?
> With your explanation as comments.
>
> I’ll play with it.
>
> Thanks
> Cedrick
>
>> Le 12 avr. 2020 à 12:19, Richard O'Keefe <rao...@gmail.com> a écrit :
>>
>>
>> I have coded and benchmarked 8 different running mean algorithms.
>> In the presence of inexact numbers it is not as accurate as
>> redoing the sums, but it's pretty close, and it's fast.
>> If "width" is not an integer or is out of range, an error
>> will be reported by #new: or #at:[put:]. It's based on Welford's
>> stable update.
>>
>> Of course this approach does NOT work for trimmed or Winsorised
>> means or for medians or any kind of robust estimate of location.
>>
>> SequenceableCollection
>> methods for: 'summarising'
>> runningMeans: width
>> |a m d|
>> a := Array new: self size - width + 1.
>> m := 0.
>> 1 to: width do: [:i |
>> m := (self at: i) + m].
>> m := m / width.
>> d := 1.
>> a at: d put: m.
>> width + 1 to: self size do: [:i |
>> m := ((self at: i) - (self at: d)) / width + m.
>> d := d + 1.
>> a at: d put: m].
>> ^a
>>
>>
>>
>>
>>
>
