Insert n empty rows using tblr

Question

I just wanted to insert n empty rows using tlbr like this:

\documentclass[letterpaper]{article}
\usepackage{expl3}
\ExplSyntaxOn
\cs_new_eq:NN \makerows \prg_replicate:nn 
\ExplSyntaxOff
\usepackage{tabularray}
\begin{document}
With tabular:
\begin{tabular}{|c|c|c|c|}
\hline
a & b & c & d \\hline
\makerows{5}{ & & &  \\hline} 
\end{tabular}
With tblr:
\begin{tblr}{|c|c|c|c|}
\hline
a & b & c & d \\hline
%\makerows{5}{ & & &  \\hline}
%% Gives
% ! Misplaced alignment tab character &.
% <argument>  &
%               & & \\hline
\end{tblr}
\end{document}

Using tabular it works, using tblr it doesn't . How can I fix this?

See my answer to a question yesterday concerning a similar issue with tblr, tblr needs to see the & in advance, I tried using expand=\makerows in your question but it still doesn't work, hopefully someone else can help!: https://tex.stackexchange.com/a/691258/273733 — JamesT, Jul 17 '23 at 13:01
@JamesT: In the meantime I found some variations which work, see my answer below. But I don't really understand why some work and others don't. — student, Jul 17 '23 at 18:55
The lua version is interesting how that works, will try that in the future, nice workaround — JamesT, Jul 17 '23 at 19:40

student · Accepted Answer · 2023-07-18T05:34:59.043

This seems to work:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{expl3,xparse}
\usepackage{tabularray}
\UseTblrLibrary{functional}
\IgnoreSpacesOn
\prgNewFunction \makerows {m} {
\intReplicate {#1} {{} &   &   &  \\hline }
}
\IgnoreSpacesOff
\begin{document}
With tabular:
\begin{tabular}{|c|c|c|c|}
\hline
a & b & c & d \\hline
\makerows{5}
\end{tabular}
With tblr:
\begin{tblr}[evaluate=\makerows]{|c|c|c|c|}
\hline
a & b & c & d \\hline
\makerows{5}
\end{tblr}
\end{document}

Adapted from the example of the tabularray manual on page 46. However I am not quite sure why I need the empty {} in the definition of my empty row.

Nevertheless I want to understand why the initial latex3 approach didn't work. The problem seems to be related to the replicate function.

Edit

Using lualatex seems to work with the expand-key as mentioned by @JamesT in the comment above:

\documentclass{article}
\usepackage{tabularray}
\usepackage{luacode}
\begin{luacode}
function makerows(n)
for i = 1, n
do
  tex.sprint("& & & \\\hline")
end
end
\end{luacode}
\begin{document}
\begin{tblr}[expand=\directlua]{c|c|c|c}
a & b & c & d \\hline
\directlua{makerows(10)}
\end{tblr}
\end{document}

Edit 2

I also tried pythontex which does not work even with the expand key:

\documentclass{article}
\usepackage{tabularray}
\usepackage[gobble=auto]{pythontex}
\begin{pycode}
def makerows(n):
    for i in range(0,n):
        print(r"& & & \\hline")
\end{pycode}
\begin{document}
\begin{tblr}[expand=\pyc]{c|c|c|c}
a & b & c & d \\hline
\pyc{makerows(3)}
\end{tblr}
\end{document}

I guess it doesn't work, because

Printed content is saved in a file and then included via \InputIfFileExists. But \InputIfFileExists is not expandable

as described here.

Insert n empty rows using tblr

1 Answers1