[FR] Support split_by for section level higher than 2 (section) in gitbook

[lcougnaud]

Thanks for the nice package!

Currently a report created by the bookdown::gitbook function can be split at the chapter and section (or rmd) levels via the split_by parameter. Would it be possible to support the splitting of the report for section level > 2 (section)?

A proposal is available in this Pull Request.

I use this package to create a report with a high number of visualizations in different subsections, and the fact that the sections are rendered into separated html files (via the split_by parameter) efficiently reduces the report loading time.
With the extension to split into level > 2, the sections 11 and 12 in this example report could be grouped into a chapter and the graphs still exported into separated files by subsection (with split_by = '3+number').

Please let me know if this feature could be of interest for the package.

Thanks for the feedback!

[katrinabrock]

Hi @yihui, Would you be willing to accept a PR to add more split_by options?

I was able to rebase @lcougnaud 's code and get it working for my purposes. If this is something you're open to, I'd be happy to 1) try chasing @lcougnaud down to sign the contributor agreement and 2) adopt the PR and make any changes in the functionality you think are needed. (e.g. if you prefer a different way of specifying header level to split by.)

Thanks for taking a look.

[yihui]

Yes. split_chapters() is perhaps the most complicated functions in bookdown. Thanks a lot for digging into it!

[katrinabrock]

@yihui great! well...most of the thanks goes to @lcougnaud. Are you happy with the description of the functionality as they have laid it out? 3, 3+number, 4, 4+number etc?

[yihui]

Yes.

[lcougnaud]

Thanks for the interest in this (old) PR, and sorry for not having it finalized before.
Please feel free to use this code, I have signed the CLA for this PR.
I would be eager to do some final checks early January as well, if that can help!

[katrinabrock]

Thanks! Welcome back. My branch with your changes rebased is here: https://github.com/katrinabrock/bookdown/tree/split_by-rebased

I plan to make a new PR, but first, I want to

• Check if there are any other docs that need to be updated
• Add some tests of this functionality

@lcougnaud If you have time to do either of these before I get to it, that would be cool.

[katrinabrock]

Fixed the failing tests on @lcougnaud 's PR here: #1490