Deprecate gt in favor of lt

[yihui]

Summary

• Remove the gt package from Imports and replace with the lightweight lt package
• New lt() S3 methods for fixed_design_summary and gs_design_summary, fully replacing as_gt()
• All 14 vignettes updated to use lt functions (lt(), lt_header(), lt_spanner(), lt_format(), lt_footnote(), lt_note(), lt_label())
• Tests updated for lt_tbl assertions

Comparison of dependencies

# gt
> setdiff(tools::package_dependencies('gt', recursive = TRUE)[[1]], xfun::base_pkgs())
 [1] "base64enc"    "bigD"         "bitops"       "cli"          "commonmark"  
 [6] "dplyr"        "fs"           "glue"         "htmltools"    "htmlwidgets" 
[11] "juicyjuice"   "magrittr"     "markdown"     "reactable"    "rlang"       
[16] "sass"         "scales"       "tidyselect"   "vctrs"        "xml2"        
[21] "generics"     "lifecycle"    "pillar"       "R6"           "tibble"      
[26] "digest"       "fastmap"      "jsonlite"     "knitr"        "rmarkdown"   
[31] "yaml"         "V8"           "xfun"         "litedown"     "reactR"      
[36] "rappdirs"     "farver"       "labeling"     "RColorBrewer" "viridisLite" 
[41] "withr"        "evaluate"     "highr"        "utf8"         "bslib"       
[46] "fontawesome"  "jquerylib"    "tinytex"      "pkgconfig"    "Rcpp"        
[51] "curl"         "cachem"       "memoise"      "mime"    

# lt
> setdiff(tools::package_dependencies('lt', recursive = TRUE)[[1]], xfun::base_pkgs())
[1] "xfun"

However, since gsDesign depends on gt and gsDesign2 depends on gsDesign, this PR alone won't reduce the number of (recursive) dependencies.

Migration mapping

https://pkg.yihui.org/lt/examples/03-gt

Test plan

• as_lt() unit tests pass for fixed and GS designs
• All design types render correctly (fixed_ahr, gs_ahr, gs_wlr, gs_rd)
• Visual comparison with gt output confirms structural equivalence
• Non-binding design body footnote renders correctly
• Custom footnotes (colname, title, analysis, spanner) all work
• R CMD check passes
• All vignettes build without error

Vignette comparison

This zip archive contains all vignettes and articles built with gt and lt, respectively. You can compare the rendered HTML pages side by side: vignette-compare.zip

Question

Why did we test the LaTeX output of gt::as_latex()?

gsDesign2/tests/testit/helper.R

Line 1 in 7043792

gt_to_latex <- function(data) cat(as.character(gt::as_latex(data)))

[jdblischak]

When I run the tests locally, I get two failures:

library("testit")
test_pkg()
## Error: -- Assertion failed: as_lt: footnote=FALSE removes footnote --
##    1. count_footnotes(z1) (LHS) ==>
##        int 0
##       ----------
##        int 1
##       <== (RHS) 1L
##       count_footnotes(z1) %==% 1L is not TRUE but FALSE at tests/testit/test-developer-as_lt.R#14
##    2. count_footnotes(z1) (LHS) ==>
##        int 0
##       ----------
##        int 2
##       <== (RHS) 2L
##       count_footnotes(z1) %==% 2L is not TRUE but FALSE at tests/testit/test-developer-as_lt.R#22

sessioninfo::package_info(c("gsDesign2", "lt"), dependencies = FALSE)
##  package   * version date (UTC) lib source
##  gsDesign2 * 1.1.8   2026-05-28 [1] local
##  lt          0.0.7   2026-05-28 [1] Github (yihui/lt@e485eb6)
##
##  [1] C:/Users/john/AppData/Local/R/win-library/4.4
##  [2] C:/Program Files/R/R-4.4.3/library
##  * ── Packages attached to the search path.

[yihui]

Just a quick update: I've submitted lt v0.1 to CRAN. Currently there are 132 newbies in the queue. I guess the initial review may take place a week later. Fingers crossed.

[jdblischak]

When comparing the tables in the rendered GitHub READMEs, I noticed that the {lt}-generated tables lack the titles and footnotes, and also have different number of default decimal places

[yihui]

the {lt}-generated tables lack the titles and footnotes

Good catch — thanks. The committed README.md was stale: it had been rendered against an older {lt} where lt() on a design summary didn't emit the caption title or footnotes. The S3 methods themselves (lt.fixed_design_summary, lt.gs_design_summary) do set them via lt_header()/lt_footnote(), and current {lt} (0.2.4) renders them. I've regenerated README.md (6d02908) and the titles + footnotes are back for both the fixed-design and group-sequential tables.

different number of default decimal places

This one is a deliberate {lt} vs {gt} difference rather than something gsDesign2 sets. Neither as_gt() nor lt() applies explicit number formatting to the fixed-design summary, so each falls back to its package default: {gt} prints the stored value verbatim (420.6346), while {lt} auto-formats to ~4 significant digits (cap of 4 - integer_width decimals), so 420.63458… displays as 420.6 with the full value preserved in the cell's title= tooltip. If we'd prefer a fixed precision here we can add an explicit lt_format(decimals = …) in the S3 method — happy to do that if you think matching the old look is worth it.

[jdblischak]

As discussed today, this immediate deprecation of as_gt() might break user code if they customize the output with other {gt} related functions. A more gentle deprecation would allow at least one release where as_gt() and lt() are both available, with as_gt() clearly marked with .Deprecated()

[yihui]

Done in 347ec76. Softened to a gentle deprecation:

• Restored the gt-based as_gt() S3 methods, so as_gt() still returns a gt_tbl — user code that customizes the output with {gt} functions (e.g. tab_options()) keeps working.
• as_gt() now emits .Deprecated() pointing to lt::lt(), and both are available this release.
• Moved {gt} from Imports to Suggests; as_gt() checks for it at call time and errors with an install hint if missing.
• Kept the source lean (dropped the long @examples, deferred arg docs to lt-methods); the gsd_* helpers stay shared with the lt() methods, so harm-bound support carries over.

Verified: summary(fixed_design_ahr(...)) |> as_gt() warns once and returns a gt_tbl that still accepts gt::tab_options().