Table gets broken when in a loop

Question

Here is the MWE:

\documentclass{article}
\usepackage{pgffor, geometry, tabu, booktabs}
\geometry{
  a4paper, 
  portrait, 
  margin=1in
}
\begin{document}

Here is creating the table using a loop\\[10pt]

    \foreach \n in {Feb, Mar, April is the best month}{
      \begin{tabu}{X[-1] X}
        \n & \foreach \m in {0,...,30}{\framebox(9,9){} }\\ \midrule
      \end{tabu}
}
\vskip 20pt
Here is creating table one row at a time\\[10pt]

      \begin{tabu}{X[-1] X}
        Feb & \foreach \n in {0,...,30}{\framebox(9,9){} }\\ \midrule
        Mar & \foreach \n in {0,...,30}{\framebox(9,9){} }\\ \midrule
        April is the best month & \foreach \n in {0,...,30}{\framebox(9,9){} }\\ \midrule
      \end{tabu}
\end{document}

Table in the loop is broken --- no alignment of columns.

How do I get the table in the loop set as the table without the loop?

why would you expect alignment in the first case? You have not made a single table but three tables each with X columns so each independently chooses a column width. — David Carlisle, Feb 18 '17 at 10:25
See http://tex.stackexchange.com/q/309765/15925 and note that the inner loop variable should be given a new name. — Andrew Swann, Feb 18 '17 at 10:32
@DavidCarlisle My bad. I agree. But when I moved \begin{tabu} before the foreach for months, and \end{tabu} after closing the foreach for months, it produced an extra } or forgotten \egroup error. — deshmukh, Feb 18 '17 at 10:38
The linked question shows you how to put the table contents in to a macro first. — Andrew Swann, Feb 18 '17 at 10:40
@AndrewSwann I tried basing my case on the structure provided in the link. But could not. And after reading your answer, I realize I could not have, either. There are two main differences, & after \n and tablecontents within the macro. — deshmukh, Feb 18 '17 at 10:50

score 2 · Accepted Answer · edited Apr 13 '17 at 12:35

This is a duplicate of Foreach loop in tabular, missing endgroup inserted, but here is the code for this particular case:

\documentclass{article}

\usepackage{pgffor, geometry, tabu, booktabs, etoolbox}

\geometry{
  a4paper,
  portrait,
  margin=1in
}

\begin{document}

\newcommand{\tablecontents}{}
\foreach \n in {Feb, Mar, April is the best month} {
\xappto\tablecontents{\n &}
\foreach \m in {0,...,30}{\gappto\tablecontents{\framebox(9,9){} } }
\gappto\tablecontents{\\ \midrule}
}

Here is creating the table using a loop\\[10pt]

\begin{tabu}{X[-1] X}
\tablecontents
\end{tabu}

\end{document}

To put the date \m in each box you need to be careful about expansion, so the inner loop line becomes

\foreach \m in {0,...,30}{\xappto\tablecontents{\noexpand\framebox(9,9){\m} } }

\xappto expands it contents, which you need to get the value of \m, but expansion of \framebox needs to be done later. \gappto does no expansion.

When I try to put the date in the box \framebox(9,9){\m}, it produces an undefined control sequence error. Will you please point me to the documentation that explains this? I will give it a try and see if I can come up with a solution. — deshmukh, Feb 18 '17 at 10:57

egreg · Answer 2 · 2017-02-18T10:59:08.157

You have to build the table body before doing the table. Here's an implementation with xparse.

\documentclass{article}
\usepackage{geometry, tabularx, booktabs}
\usepackage{xparse}
\geometry{
  a4paper, 
  portrait, 
  margin=1in
}

\ExplSyntaxOn
\seq_new:N \l__deshmukh_monthtable_in_seq
\seq_new:N \l__deshmukh_monthtable_out_seq

\cs_new_protected:Nn \__deshmukh_printmonth:n
 {
  { #1 } & \prg_replicate:nn { 30 } { \framebox(9,9){} ~ }
 }

\NewDocumentCommand{\monthtable}{m}
 {
  \seq_set_split:Nnn \l__deshmukh_monthtable_in_seq {,} { #1 }
  \seq_clear:N \l__deshmukh_monthtable_out_seq
  \seq_map_inline:Nn \l__deshmukh_monthtable_in_seq
   {
    \seq_put_right:Nn \l__deshmukh_monthtable_out_seq
     { \__deshmukh_printmonth:n { ##1 } }
   }
  \noindent
  \begin{tabularx}{\textwidth}{l>{\raggedright\arraybackslash}X}
  \toprule
  \seq_use:Nn \l__deshmukh_monthtable_out_seq { \\ \midrule }
  \\ \bottomrule
  \end{tabularx}
 }
\ExplSyntaxOff

\begin{document}

\monthtable{Feb,Mar,April is the best month}

\end{document}

I thought the OP wanted the month titles and 31 boxes to form 32 aligned columns — David Carlisle, Feb 18 '17 at 10:36

Table gets broken when in a loop

2 Answers2