fig.ncol not working with Latex

[nassuphis]

this should produce 2 figures per column:

\documentclass{article}
\begin{document}
<<,fig.show = "hold",out.width = "2cm",fig.ncol=2>>=
plot(1:100); plot(100:1); plot(1:100); plot(100:1); plot(1:100) 
@
\end{document}

it used to work.

now it produces this:

---

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[nassuphis]

> xfun::session_info()
R version 4.3.3 (2024-02-29)
Platform: aarch64-apple-darwin20 (64-bit)
Running under: macOS Sonoma 14.1, RStudio 2023.12.1.402

Locale: en_US.UTF-8 / en_US.UTF-8 / en_US.UTF-8 / C / en_US.UTF-8 / en_US.UTF-8

Package version:
  callr_3.7.6       cli_3.6.2         compiler_4.3.3    curl_5.2.1        desc_1.4.3        evaluate_0.23     graphics_4.3.3   
  grDevices_4.3.3   highr_0.10        knitr_1.46.3      methods_4.3.3     pkgbuild_1.4.4    processx_3.8.4    ps_1.7.6         
  R6_2.5.1          remotes_2.5.0     rstudioapi_0.16.0 stats_4.3.3       tools_4.3.3       utils_4.3.3       xfun_0.43        
  yaml_2.3.8       
> 

[cderv]

fig.ncol is used for sufigure and so you need to use fig.cap and fig.subcap for it to be used, also adding usage for the subfig package.

We document this in https://bookdown.org/yihui/rmarkdown-cookbook/latex-subfigure.html

fig.ncol is not used otherwise.

Example:

\documentclass{article}
\usepackage{subfig}
\begin{document}
<<out.width = "50%",fig.ncol=2, fig.subcap=letters[1:5], fig.cap="test">>=
plot(1:100); plot(100:1); plot(1:100); plot(100:1); plot(1:100)
@
\end{document}

Codebase for this in https://github.com/yihui/knitr/blob/44a7bee566afff3eb4c8b13fd6fa64487e12981f/R/hooks-latex.R

Hope this helps