Posted this on slack, but I think I’ll move over to using discourse more (I’ll post a cross link) when doing split-apply-combine with a DataFrame is there anyway for the apply transformations to reference previously calculated variables? df = DataFrame(a=repeat([1,2],inner=[5]), b='A':'J', c=rand(…

Using Query.jl I can do this, but i think its quite verbose…any suggestions? df |> @groupby({_.a}) |> @map({a=key(_)[1], n=length(_), m=mean(_.c)}) |> @map({a=_.a, n=_.n, m=_.m, y=_.n-_.m})

Maybe this one generalizes a bit better @from i in df begin @group i by i.a into g @let n=length(g) @let m=mean(g.c) @select {a=key(g), n=n, m=m, y=n-m} @collect DataFrame end

No this is not possible currently (I thought it was…). You are going to have to use two transform statements. Note that you can make the second one a transform! which will reduce the memory footprint a bit.

I ended up using the approach taken here: [image] Dpylr do equivalent in query.jl standalone syntax? Data Whoa cool. So what does the _ _ refer to on the @mapmany line? It looks like it’s the original dataframe somehow, but how does it know that that’s what you’re referrin…

How to reference new variables in a combine for dataframes?

General Usage

bdeonovic January 6, 2021, 8:13pm 5

I ended up using the approach taken here:

Topic		Replies	Views
Creating new dataframe column! General Usage question , dataframes	3	335	April 21, 2021
Easier way to split-apply-combine in DataFrames.jl General Usage dataframes	5	1152	December 14, 2020
[Query.jl] Way to map many variables to a single function Data query	0	464	March 7, 2021
Why doesn't this work with DataFrames.jl `combine`? Data	13	1036	August 3, 2021
DataFrame groups as an argument of a function General Usage question , dataframes	15	1033	November 23, 2021

How to reference new variables in a combine for dataframes?

Related topics