Mapreduce, pass extra arguments to reduce/vcat of DataFrames

[baptnz]

@pdeffebach

You can also use an anonymous. They work just like in R

reduce((a, b) -> ..., dfs)

but it looks like this doesn’t work

I’m also a bit puzzled by this; I thought I’d managed to get it to work with

mapreduce(f, (x,y) -> vcat(x,y, source="id", cols=:intersect), ps)

but on my longer example I get some unexpected missing values that I don’t understand at all.