Add wrapper for eachslice?

[rofinn]

I'm not sure what the best approach for this is, but it'd be nice if you could do:

eachslice(A; dims=[:channel])`

rather than

eachslice(A; dims=[dim(dimnames(A), :channel)])

[mcabbott]

Yes this ought to be made to work.

The catch is that you don't want to simply call eachslice(keyless(A), dims=d) after looking up d, as it would be nice to preserve the structure on each slice. But you can't dispatch on dims. So I guess you either copy-paste Base's definition, or you return another iterator which wraps each slice as it goes along.

[rafaqz]

FYI, I had this problem too, and had to copy-paste eachslice:

https://github.com/rafaqz/DimensionalData.jl/blob/master/src/methods.jl#L84-L97

It could be good to fix all these methods in base some day so we can dispatch properly on dims

[mcabbott]

Yes I tried to change NamedDims to that strategy, and the PR got lost in an argument about how to handle Julia < 1.1 most cleanly...

Re changing Base, I tried that too: JuliaLang/julia#32310 (comment)

[rafaqz]

Hmm no response in the Base PR. I had this too, ages ago:

https://github.com/JuliaLang/Statistics.jl/issues/11

But decided not to implement it yet as I wasn't sure I needed that many changes, and I don't in the end, I'm just dispatching on the array type instead of the dims type (I wanted to free up array inheritance for other things - ie dims are a trait, but its too hard).

eachslice and accumulate.jl are still problems I think.

I just didn't provide eachslice before 1.1. Will probably going to drop 1.0 support anyway soon, its starting to be a headache.

[mcabbott]

If someone was very energetic, I wonder what chance a PR adding a step via some to_dims(A, dims) to every single function in Base would have? Like to_index except only useful for things outside Base, I suppose.

[rafaqz]

That's a really clean way of doing it.