[GSoC] Dataframes for D

[jmh530]

On Tuesday, 25 June 2019 at 17:25:34 UTC, Prateek Nayak wrote:
>>>> [snip]
>
> -------------
> Week 4 Update
> -------------
>
> This marks the completion of Stage I of Google Summer of Code 
> 2019. It seems like it was only yesterday when I started 
> working on this project and it has already been a month.
>
> --------------------------
> So what happened last week
> --------------------------
> * apply - to apply a function on a row/column
> * function to convert a column of data to level of Index
> * drop - to drop a row/column
>
[snip]

Glad to see you're still making great progress.

I had worked on the byDim function in mir.ndslice.topology is 
byDim because I had wanted the same sort of functionality as R's 
apply. It works a little differently than R's, but I find it very 
good for a lot of things. Your version of apply (I'm looking at 
the apply branch of magpie) looks like it operates a bit like a 
byDim chained with an each, so byDim!N.each!f. However, it also 
has this index variable allowing it to skip rows or something 
(I'm not really sure if this feature pulls its weight...).

So I have two questions: 1) does byDim also work with 
dataframes?, 2) can you add an overload that is apply(f, axis) 
without the index parameter?

One of my take-a-ways from looking at the apply function (again 
just looking at that apply branch) is that you might benefit from 
using more of what is Ilya has already put in mir.ndslice where 
available. For instance, the overload of apply that is just 
apply!f is basically the same as mir's each, but each has more 
features.