# Cummean, cumall, and cumany
**URL:** https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219
**Category:** General Usage
**Created:** [September 7, 2020, 7:55pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219 "2020-09-07T19:55:45Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@tk3369](https://discourse.julialang.org/u/tk3369)
#### Post date: [September 7, 2020, 7:55pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/1 "2020-09-07T19:55:45Z")
Currently, these functions exist in Base:
- cumsum
- cumprod
- cummin (using accumulate)
- cummax (using accumulate)
I’m just checking out dplyr’s functions and they have
- cummean
- cumall (logical bit vector)
- cumany (logical bit vector)
Does it make sense to add these to Base? Or perhaps all these functions should be moved to Statistics?
---
### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [September 7, 2020, 8:03pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/2 "2020-09-07T20:03:38Z")
Well, we have [`accumulate`](https://docs.julialang.org/en/latest/base/arrays/#Base.accumulate), in terms of which `cumall` is just `accumulate(&, A)` and `cumany` is `accumulate(|, A)`, so it doesn’t seem worthwhile adding specific functions for these.
`cummean(A) = cumsum(A) ./ (1:length(A))` is _slightly_ more complicated, at least if you want to eliminate the allocation of a temporary array. If it’s a common operation it might make sense in Statistics. However, I can’t seem to find any record of anyone ever asking for this function before, so that doesn’t seem to indicate a big demand?
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### Author:  [@tbeason](https://discourse.julialang.org/u/tbeason)
#### Post date: [September 7, 2020, 8:10pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/3 "2020-09-07T20:10:19Z")
Ironically, I am currently porting some code from Matlab that contains the equivalent of `cummean` as described here. So, 👍 from me!
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### Author:  [@tk3369](https://discourse.julialang.org/u/tk3369)
#### Post date: [September 7, 2020, 8:23pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/4 "2020-09-07T20:23:53Z")
Yeah I couldn’t find any previous requests from the julia repo either.
Looks like Bayesian people want it?
[https://juliahub.com/ui/CodeSearch?q=cummean%20&u=define&t=all](https://juliahub.com/ui/CodeSearch?q=cummean%20&u=define&t=all)
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### Author:  [@piever](https://discourse.julialang.org/u/piever)
#### Post date: [September 7, 2020, 8:37pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/5 "2020-09-07T20:37:29Z")
Just to do some publicity to a couple of really nice packages, you could do the cumulative mean with OnlineStats + Transducers:
```julia
julia> using OnlineStats, Transducers
julia> collect(Transducer(Mean()), 1:4)
```
(It’s one of the examples in the [docs](https://juliafolds.github.io/Transducers.jl/stable/reference/manual/#Transducers.Transducer-Tuple%7BOnlineStatsBase.OnlineStat%7D).)
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### Author:  [@tbeason](https://discourse.julialang.org/u/tbeason)
#### Post date: [September 7, 2020, 9:26pm UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/6 "2020-09-07T21:26:04Z")
Did not know this. Thanks for sharing.
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### Author:  [@xiaodai](https://discourse.julialang.org/u/xiaodai)
#### Post date: [September 8, 2020, 7:04am UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/7 "2020-09-08T07:04:23Z")
Is it fast? I thought the canonical way in Julia is `accumulate`
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### Author:  [@tkf](https://discourse.julialang.org/u/tkf)
#### Post date: [September 9, 2020, 6:15am UTC](https://discourse.julialang.org/t/cummean-cumall-and-cumany/46219/8 "2020-09-09T06:15:20Z")
`Transducer(::OnlineStat)` is not really for performance. It’s mainly for exposing the super rich set of functionality that exists in OnlineStats.jl to Transducers.jl-based API. OnlineStats are really “just” reducing functions obscured by the implementation detail that uses in-place mutation. So, it’d be such a pity if two libraries cannot talk to each other.