handle aggregation of different batches

[Borda]

🚀 Feature

resolve handling the aggregation of different batches (for classification there are 'micro', 'macro' and 'weighted' for example) and include these in the class-based interface

Motivation

Pitch

Alternatives

Additional context

[SkafteNicki]

I guess this can be close with the new interface in place

[stale]

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