Can't have square left bracket [ to begin a row in a table

Question

\begin{table}[ht]
\label{tab:intro}
\caption{Anonymized data - output example}
\begin{tabular}{llll}
\toprule    
      Age & SEX & ETHNIC & STUDIES \\
\midrule
    * &   * &      * &       * \\
   42 &   1 &      1 &       7 \\
   40 &   1 &      1 &       7 \\
   45 &   1 &      1 &       7 \\
 [48, 51[ &   2 &      1 &     <=3 \\
 [48, 51[ &   1 &      1 &     <=3 \\
    * &   * &      * &       * \\
 [60, 63[ &   2 &      6 &     <=6 \\
   58 &   1 &      1 &       5 \\
    * &   * &      * &       * \\
\bottomrule
\end{tabular}
\end{table}

Everything works fine if I remove [, but i need to put them.

This is the error:

! Paragraph ended before \@argarraycr was complete.

Or \\[0pt], which also "eats" the optional argument of \\. — TeXnician, Feb 08 '17 at 12:12
like this: \[0pt]48, 51[ & 2 & 1 & <=3 \ or 45 & 1 & 1 & 7 \{} [48, 51[ & 2 & 1 & <=3 \ — M. GENTILI, Feb 08 '17 at 12:13
No duplicate error. I've tried both solution, but are not working, maybe I miss understood them — M. GENTILI, Feb 08 '17 at 12:15
Solved! 45 & 1 & 1 & 7 \[0pt] [48, 51[ & 2 & 1 & <=3 \[0pt] [48, 51[ & 1 & 1 & <=3 \ * & * & * & * \[0pt] ............THANKS — M. GENTILI, Feb 08 '17 at 12:17
You are wrong: Replacing \\ by \\\relax does work, if I make your code snippet complete by \documentclass{article}\usepackage{booktabs}\begin{document} and \end{document}. So it is a duplicate. — Schweinebacke, Feb 08 '17 at 12:22
using \relax is better than using [0pt] (it means latex does nothing rather than adding a zero skip) — David Carlisle, Feb 08 '17 at 12:24
an alternative to \relax is to enclose the material in the first column in braces, to hide the initial [: ...\\{[48, 51[} — barbara beeton, Feb 08 '17 at 13:25
@barbarabeeton that's OK in tables but trickier if the cells are in math mode as {} affects spacing in math — David Carlisle, Feb 08 '17 at 13:54
@DavidCarlisle -- good point. on the other hand, that's one reason why amsmath accepts a typed space between \\ and an open bracket to dissociate it from the "vspace" directive. — barbara beeton, Feb 08 '17 at 14:05

score 2 · Answer 1 · edited Apr 13 '17 at 12:34

As already explained in the answer to Error with table adding \relax to \\ before rows, that start with [, solves the problem:

\documentclass{article}
\usepackage{booktabs}
\begin{document}
\begin{table}[ht]
\label{tab:intro}
\caption{Anonymized data - output example}
\begin{tabular}{llll}
\toprule    
      Age & SEX & ETHNIC & STUDIES \\
\midrule
    * &   * &      * &       * \\
   42 &   1 &      1 &       7 \\
   40 &   1 &      1 &       7 \\
   45 &   1 &      1 &       7 \\\relax
 [48, 51[ &   2 &      1 &     <=3 \\\relax
 [48, 51[ &   1 &      1 &     <=3 \\
    * &   * &      * &       * \\\relax
 [60, 63[ &   2 &      6 &     <=6 \\
   58 &   1 &      1 &       5 \\
    * &   * &      * &       * \\
\bottomrule
\end{tabular}
\end{table}
\end{document}

BTW: As shown in the example < in text mode will not result in a <. You should either use \textless:

\documentclass{article}
\usepackage{booktabs}
\begin{document}
\begin{table}[ht]
\label{tab:intro}
\caption{Anonymized data - output example}
\begin{tabular}{llll}
\toprule    
      Age & SEX & ETHNIC & STUDIES \\
\midrule
    * &   * &      * &       * \\
   42 &   1 &      1 &       7 \\
   40 &   1 &      1 &       7 \\
   45 &   1 &      1 &       7 \\\relax
 [48, 51[ &   2 &      1 &     \textless=3 \\\relax
 [48, 51[ &   1 &      1 &     \textless=3 \\
    * &   * &      * &       * \\\relax
 [60, 63[ &   2 &      6 &     \textless=6 \\
   58 &   1 &      1 &       5 \\
    * &   * &      * &       * \\
\bottomrule
\end{tabular}
\end{table}
\end{document}

or math mode:

\documentclass{article}
\usepackage{booktabs}
\usepackage{amsmath}
\begin{document}
\begin{table}[ht]
\label{tab:intro}
\caption{Anonymized data - output example}
\[
\begin{array}{llll}
\toprule    
      \text{Age} & \text{SEX} & \text{ETHNIC} & \text{STUDIES} \\
\midrule
    * &   * &      * &       * \\
   42 &   1 &      1 &       7 \\
   40 &   1 &      1 &       7 \\
   45 &   1 &      1 &       7 \\\relax
 [48, 51[ &   2 &      1 &     \leq 3 \\\relax
 [48, 51[ &   1 &      1 &     \leq 3 \\
    * &   * &      * &       * \\\relax
 [60, 63[ &   2 &      6 &     \leq 6 \\
   58 &   1 &      1 &       5 \\
    * &   * &      * &       * \\
\bottomrule
\end{array}\]
\end{table}
\end{document}

score 1 · Answer 2 · answered Feb 08 '17 at 12:18

Thanks to user124577:

\begin{table}[ht]
\label{tab:intro}
\caption{Anonymized data - output example}
\begin{tabular}{llll}
\toprule
  Age & SEX & ETHNIC & STUDIES \\
\midrule
    * &   * &      * &       * \\
   42 &   1 &      1 &       7 \\
   40 &   1 &      1 &       7 \\
   45 &   1 &      1 &       7 \\[0pt]
 [48, 51[ &   2 &      1 &     <=3 \\[0pt]
[48, 51[ &   1 &      1 &     <=3 \\
    * &   * &      * &       * \\[0pt]
[60, 63[ &   2 &      6 &     <=6 \\
   58 &   1 &      1 &       5 \\
    * &   * &      * &       * \\
\bottomrule
\end{tabular}
\end{table}

Can't have square left bracket [ to begin a row in a table

2 Answers2