Bogumił Kamiński

Redesign of `stack` and `unstack`

13

This issue is meant to replace: https://github.com/JuliaData/DataFrames.jl/issues/2215 https://github.com/JuliaData/DataFrames.jl/issues/2148 https://github.com/JuliaData/DataFrames.jl/issues/3066 https://github.com/JuliaData/DataFrames.jl/issues/2422 https://github.com/JuliaData/DataFrames.jl/issues/2414 https://github.com/JuliaData/DataFrames.jl/issues/1839 The proposed improved API for `stack` is: ``` stack(df::AbstractDataFrame, measure_vars, id_vars; variable_name=:variable, name_value=identity, value_name=:value, # or function variable_eltype::Type=String,...

Replace replace with a comprehension

3

See https://github.com/JuliaData/DataFrames.jl/pull/1709#discussion_r253771079. This should be changed when https://github.com/JuliaLang/julia/pull/30485 is fixed.

Add `findcols`

1

What do you think about adding the following function: ``` findcols(predicate, df::AbstractDataFrame) = findall(predicate, eachcol(df)) ``` Maybe such function would be more readable than using `predicate.(eachcol(df))` for column selection?

check if DataFrames.jl is affected by Threads.@spawn bug

6

x-ref https://github.com/JuliaLang/julia/issues/40626, https://github.com/JuliaData/CSV.jl/pull/1046, https://github.com/JuliaData/CSV.jl/issues/1045

show for text/html does not properly handle all promised kwargs

5

@ronisbr for example the following fails: ``` show(stdout, MIME("text/html"), df, allcols=true) ``` although users can expect that the following kwargs would work: ``` allrows::Bool = !get(io, :limit, false), allcols::Bool =...

We have most problematic performance in this case.

add sotring support for `unstack`

1

I thought it is not needed, but now I think it is 😄.

add multithreaded join algorithms

4

We currently have a limited support for multi-threading in joins. It would be good to improve it in the future.

x-ref https://github.com/JuliaLang/julia/pull/47695

x-ref https://github.com/JuliaData/DataFrames.jl/issues/3411