Apply JuliaFormatter

[rikhuijzer]

The formatting of DecisionTree.jl is sometimes inconsistent and using styles which are generally advised against such as aligning items vertically. This PR applies JuliaFormatter to the repository to get a coherent style. I've also tried to replace calls such as f(; x = x) by f(; x). This is possible since Julia 1.5 (NEWS.md) and this repository has a lower bound on Julia 1.6.

The command that I used to format the repository is:

julia> using JuliaFormatter

julia> format(".", BlueStyle(); always_use_return=false, import_to_using=false)

I've chosen the blue style because it's a pretty well-known and well thought out style, see the BlueStyle repo for details.

We could also add a .JuliaFormatter.toml file to the root of the repository containing:

style = "blue"
always_use_return = false
import_to_using = false

To use the newer keyword arguments syntax, that is replace f(; x = x) by f(; x), I've used comby:

$ comby -matcher .jl '(:[a]; :[b], :[c]=:[c])' '(:[a]; :[b], :[c])'

and some variations of this command.

I've also considered adding a CI workflow to check whether PRs satisfy the code style. However, this would be an extra burden to contributors so I think that an occasional run of the JuliaFormatter should be enough.

[codecov-commenter]

Codecov Report

Merging #219 (a49141b) into dev (7591df6) will decrease coverage by 0.66%. The diff coverage is 89.84%.

:exclamation: Current head a49141b differs from pull request most recent head 413a2d9. Consider uploading reports for the commit 413a2d9 to get more accurate results

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@@            Coverage Diff             @@
##              dev     #219      +/-   ##
==========================================
- Coverage   88.15%   87.50%   -0.66%     
==========================================
  Files          10       10              
  Lines        1266     1328      +62     
==========================================
+ Hits         1116     1162      +46     
- Misses        150      166      +16     

Impacted Files	Coverage Δ
src/scikitlearnAPI.jl	51.33% <53.12%> (-0.34%)	:arrow_down:
src/DecisionTree.jl	61.44% <55.55%> (+1.44%)	:arrow_up:
src/regression/main.jl	88.88% <84.61%> (+0.42%)	:arrow_up:
src/util.jl	90.78% <92.57%> (+0.44%)	:arrow_up:
src/regression/tree.jl	95.03% <96.89%> (+0.07%)	:arrow_up:
src/classification/tree.jl	94.89% <96.96%> (+0.07%)	:arrow_up:
src/measures.jl	97.39% <97.01%> (+0.04%)	:arrow_up:
src/classification/main.jl	95.91% <97.36%> (-0.26%)	:arrow_down:
src/abstract_trees.jl	91.66% <100.00%> (+0.36%)	:arrow_up:
src/load_data.jl	91.30% <100.00%> (ø)
... and 7 more

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[ablaom]

We could also add a .JuliaFormatter.toml file to the root of the repository containing:

style = "blue" always_use_return = false import_to_using = false

No objection to adding this.

I tend to agree adding to CI is unnecessary but don't have a strong opinion about it. Someone who does is welcome to open a new PR.

[ablaom]

@rikhuijzer Thanks for this contribution.