Fix table widths for latex tables and add unit testing

[snhansen]

Summary

In the old code, col_alignment contains the aligment of stub columns and visible columns, in that order. In the loop for (i in seq_along(col_alignment)), the ith row of colwidth_df is referenced. However, there are multiple problems with that:

• colwidth_df contains hidden columns, so the ith row of that data frame doesn't not necessarily correspond to the ith item of col_alignment.
• stub columns is not necessarily at the beginning of colwidth_df

In this PR,

• we change the function create_colwidth_df_l() to include column alignments.
• we rewrite create_table_start_l() to extract only the visible columns of colwidth_df and we make sure the order of the rows in colwidth_df_visible is "row_group", "stub", "default". The loop is then taken over the rows of colwidth_df_visible.
• we add some unit testing in test-l_cols_width.R. We test five different tables where we test whether col_widths() works correctly in different scenarios, e.g. when merging columns, when using stubs with/without row groups as a column.

Screenshots

Below are some before and after screenshots of the five examples in test-l_cols_width.R with latex.use_longtable being TRUE and FALSE in that order. When not using longtable, I've set the table.width manually in the screenshots, otherwise the resulting table will be a full-width table from which the column widths can't really be judged.

Table 1

Table 2

Table 3

Table 4

Table 5

Additional comments:

• Stub columns are automatically left-aligned for LaTeX output. This is so for the code in this PR as well as the old code.
• It might be an idea not to go full-width for tables using tabular if all column widths are specified (Default width when outputting to PDF #1857).
• Tables using tabular are left-aligned by default. Are we able to control this? (Center table when outputting as PDF #1848)

Related GitHub Issues and PRs

• cols_width() not working when using cols_merge() for PDF output #1837

Checklist

• I understand and agree to the Code of Conduct.
• I have listed any major changes in the NEWS.
• I have added testthat unit tests to tests/testthat for any new functionality.

[CLAassistant]

All committers have signed the CLA.

[olivroy]

Hi @snhansen! Thanks for working on this! We will try to review soon. But first, please use %>% as we still support R 3.6! |> was introduced in R 4.1! Thanks

[snhansen]

@olivroy: Of course! Should be done now.

[olivroy]

I didn't notice before, but it seems like your changes affect other tests https://github.com/rstudio/gt/actions/runs/10629794644/job/29475689750. You'd have to review and accept those if they make sense!

[snhansen]

@olivroy: Thanks, the tests did indeed reveal a mistake on my part. I think it should be good now though. Could you press the button to run tests again? 🤞

[olivroy]

I unfortunately don't have that power, but we will review soon! from what I can see, it looks pretty good. The testing seems thorough and the explanations are clear. (All tests also pass locally for me)

Stub columns are automatically left-aligned for LaTeX output. This is so for the code in this PR as well as the old code.

If you wish to change that, feel free to open a new PR!

It might be an idea not to go full-width for tables using tabular if all column widths are specified (#1857).

Agreed. Full widths tables were never a thing before in gt. See this comment about that #1588 (comment)

Tables using tabular are left-aligned by default. Are we able to control this? (#1848)

It would be great if there was a Quarto div for this. quarto-dev/quarto-cli#8705 (comment) is a solution.

[rich-iannone]

Looks great, thanks!