Implement DT[, across(.SD, fun1, fun2, fun3), by=group]
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Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 35/100
Research direction
Start by reading the dplyr::across reference and the linked DataFrames.jl discussion, then search the data.table codebase for grouped expressions and .SD handling. The issue names no files or tests; done means agreeing on and implementing the proposed across(.SD, min, max) behavior for grouped data.table expressions, with coverage for the shown example.
Written by the indexing model from the issue text.
Description
Inspired by dplyr::across and triggered by https://github.com/JuliaData/DataFrames.jl/pull/2725#discussion_r622424355
Instead of :
DT[, unlist(lapply(.SD, function(x) c(max=max(x), min=min(x)))), by=group]
it could be
DT[, across(.SD, min, max), by=group]
I didn't find any related issues or PRs in a quick search. If there are any, and S.O. questions, please link them here.
- Dominant language
- R
- Stars
- 3.9k
- Forks
- 1.1k
- Avg merge
- 14h 4m
- Merged PRs (30d)
- 4
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
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- Open a pull request that references the issue number.
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