DPL Analysis: Filling histograms in registry with expressions#4433
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Very nice. How difficult would it be to use |
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| auto filtered = o2::soa::Filtered<T>{{table.asArrowTable()}, o2::framework::expressions::createSelection(table.asArrowTable(), filter)}; | ||
| for (auto& t : filtered) { | ||
| hist->Fill(*(static_cast<C>(t).getIterator())); |
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It may be more efficient to use FillN method of ROOT histogram, that allows to fill it from an array
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Ok, do I see well there is no FillN() for TH3?
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Not sure how it is implemented for dimensions > 1, I'll have to check. For 1-dimensional you can pass nullptr for the weights.
@ktf We would need still to copy filtered rows, and so iterate. There is no actual filtered table. |
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True for filtered tables, but not for unfiltered ones, though. That said, we could also try to suggest ROOT folks an extension. |
Hm, but using expressions by principle creates filtered views ('tables')? ROOT has RDataFrame that enables to filter and draw the data - but with filter from lambda / string. |
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Yes, I know. I wrote the arrow integration for RDataFrame... ;-) I meant that we could extend FillN to take a bitmap / selection vector for what to fill. |
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Anyways, this is already very good. Let's merge this and continue the discussion on how to extend it. |
hah, ok ;-) |
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