Inappropriate column size when using \multicolumn

Question

I have a column size problem when using \multicolumn, please see the following pic:

The size of the second column is bigger than the size of the first column, which should be balanced (like the rest of the columns).

The corresponding latex code:

\begin{table}[!t]
    \renewcommand\tabcolsep{5.5pt}
    \caption{Performance}
    \begin{center}
        \begin{tabular}{|c|c|c|c|c|c|c|c|c|}
            \hline
            \multirow{2}{*}{Method} & \multicolumn{2}{c|}{\emph{shapes\_translation}} & \multicolumn{2}{c|}{\emph{shapes\_6dof}}   & \multicolumn{2}{c|}{\emph{poster\_6dof}}   & \multicolumn{2}{c|}{\emph{slider\_depth}} \\ \cline{2-9}
            & AOR                 & AR                 & AOR              & AR               & AOR              & AR               & AOR                & AR            \\ \hline
            SiamFC\cite{bertinetto2016fully}                  & 0.812             & 0.940            & 0.835          & 0.968          & 0.830          & 0.956          & 0.909            & \textbf{1.000}       \\ \hline
            ECO\cite{danelljan2017eco}                     & 0.823               & 0.943              & 0.847            & 0.969            & 0.846            & 0.960            & \textbf{0.947}              & \textbf{1.000}         \\ \hline
            SiamRPN++\cite{Li_2019_CVPR}     & 0.790             & 0.942            & 0.779          & 0.972          & 0.753          & 0.899          & 0.907            & \textbf{1.000}       \\ \hline
            ATOM\cite{Danelljan_2019_CVPR}       & 0.815             & 0.945            & 0.803          & 0.974          & 0.835          & 0.961          & 0.897            & \textbf{1.000}       \\ \hline
            E-MS\cite{barranco2018real}                  & 0.675    & 0.768   & 0.612 & 0.668 & 0.417 & 0.373 & 0.447   & 0.350  \\ \hline
            RMRNet-TS                  & 0.491    & 0.564   & 0.467 & 0.509 & 0.504 & 0.558 & 0.814   & 0.993  \\ \hline
            RMRNet                  & \textbf{0.836}    & \textbf{0.951}   & \textbf{0.866} & \textbf{0.980} & \textbf{0.859} & \textbf{0.962} & 0.915   & \textbf{1.000}  \\ \hline
        \end{tabular}
    \end{center}
\end{table}

I have found that 'shapes_translation' is longer than the other titles (such as shapes_6dof), which makes the unbalanced column size. But I do not know how to fix it. Any help will be appreciated, thank you in advance.

Update:

I have modified the code according to Ben's answer in Table column widths disproportionate due to multicolumn cell being too long

The new table and the new code:

\newlength\widthSubTabTwo
\settowidth\widthSubTabTwo{shapes\_translation}
\newlength\lengthTwo
\setlength\lengthTwo{\dimexpr(\widthSubTabTwo+2\tabcolsep)/2-2\tabcolsep\relax}
\begin{table}[!t]
    \renewcommand\tabcolsep{5.5pt}
    \caption{Performance}
    \begin{center}
        \begin{tabular}{|c|{2}{w{c}{\lengthTwo}}|c|c|c|c|c|c|}
            \hline
            \multirow{2}{}{Method} & \multicolumn{2}{c|}{\emph{shapes_translation}} & \multicolumn{2}{c|}{\emph{shapes_6dof}}   & \multicolumn{2}{c|}{\emph{poster_6dof}}   & \multicolumn{2}{c|}{\emph{slider_depth}} \ \cline{2-9}
            & AOR                 & AR                 & AOR              & AR               & AOR              & AR               & AOR                & AR            \ \hline
            SiamFC\cite{bertinetto2016fully}                  & 0.812             & 0.940            & 0.835          & 0.968          & 0.830          & 0.956          & 0.909            & \textbf{1.000}       \ \hline
            ECO\cite{danelljan2017eco}                     & 0.823               & 0.943              & 0.847            & 0.969            & 0.846            & 0.960            & \textbf{0.947}              & \textbf{1.000}         \ \hline
            SiamRPN++\cite{Li_2019_CVPR}     & 0.790             & 0.942            & 0.779          & 0.972          & 0.753          & 0.899          & 0.907            & \textbf{1.000}       \ \hline
            ATOM\cite{Danelljan_2019_CVPR}       & 0.815             & 0.945            & 0.803          & 0.974          & 0.835          & 0.961          & 0.897            & \textbf{1.000}       \ \hline
            E-MS\cite{barranco2018real}                  & 0.675    & 0.768   & 0.612 & 0.668 & 0.417 & 0.373 & 0.447   & 0.350  \ \hline
            RMRNet-TS                  & 0.491    & 0.564   & 0.467 & 0.509 & 0.504 & 0.558 & 0.814   & 0.993  \ \hline
            RMRNet                  & \textbf{0.836}    & \textbf{0.951}   & \textbf{0.866} & \textbf{0.980} & \textbf{0.859} & \textbf{0.962} & 0.915   & \textbf{1.000}  \ \hline
        \end{tabular}
    \end{center}
\end{table}

Then, the problem is solved, but I have a new problem. The red vertical line is missing. I am a newbie at this, please help.

Welcome to TeX.SE. What happens if you abbreviate shapes\_translation to shapes\_transl. and recompile the document? — Mico, Aug 22 '21 at 09:17
@Mico Thanks for your reply. If I use 'shapes_transl.', the table will be balanced. However, I prefer to keep the full name... — xueyinhualuo, Aug 22 '21 at 09:29
Off-topic: the instruction \renewcommand\tabcolsep{5.5pt} is a bit fishy. Do please change it to \setlength\tabcolsep{5.5pt}. — Mico, Aug 22 '21 at 09:37
How wide is the text block of your document? Alternatively, which paper size does your document employ, and how wide are the margins? — Mico, Aug 22 '21 at 09:42
See also: Table column widths disproportionate due to multicolumn cell being too long — leandriis, Aug 22 '21 at 10:15
@leandriis Thanks for your reply. I have updated the question. A new question comes. — xueyinhualuo, Aug 22 '21 at 11:46
@Mico I have fixed the original question. However, a new one comes. Please see the update. — xueyinhualuo, Aug 22 '21 at 11:48
@xueyinhualuo - I've just posted an answer, in which I consider three possible fixes to your original table. — Mico, Aug 22 '21 at 12:10
An immediate "fix" to the missing-vertical-line issue in the modified code consists of replacing *{2}{w{c}{\lengthTwo}}| with w{c}{\lengthTwo}|w{c}{\lengthTwo}|. However, there's still the problem that the first two data columns are noticeably wider than the other six. — Mico, Aug 22 '21 at 12:13

Mico · Answer 1 · 2021-08-22T12:18:49.707

Let us consider four versions of the table.

The status quo, i.e., the current situation (while giving the table a more open "look" and leaving off the final three data rows for a more compact appearance). Observe the excessive width of 2nd data column.
Table 2 is similar to Table 1, but with the first two data columns now having equal width and being jointly centered below the common header cell. Note that data columns 1 and 2 are noticeably wider than data columns 3 thru 8.
In Table 3, we abbreviate shapes\_translation to shapes\_transl., allowing all 8 data columns to be equally wide.
Table 4 uses a (much) smaller font size for \emph{shapes\_translation}, also allowing all 8 data columns to be equally wide.

Fine typography often requires us to make trade-offs.

While we may readily conclude that Table 1 is problematic and Table 4 is no good (because of the minute font size used in one of the header cells), it's not clear that Table 2 is really all that much better than Table 1. Why?
In Table 2, we've exchanged one typographic problem (the 2nd data column being much wider than the other 7) with another one (the widths of first two data columns are noticeably larger than the widths of the other six).
Table 3, whose trade-off consists of abbreviating the header cell, may be best -- or, at least, "least bad" -- overall, as it allows the widths of the 8 data columns to be (very nearly) equal, giving the table a nicely balanced "look".

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{newtxtext,newtxmath}
\usepackage{booktabs}
\usepackage{array,calc,caption}
\captionsetup{skip=0.25\baselineskip}
\newlength\mylen
\setlength\mylen{\widthof{\emph{shapes\_translation}}/2}
\begin{document}
\begin{table}[!ht]
\setlength\tabcolsep{0pt} % let LaTeX figure out optimal amount of intercolumn whitespace
\caption{Status quo: 2nd data column much wider than the other 7}
\begin{tabular}{\textwidth}{@{\extracolsep{\fill}} l {8}{c} }
\toprule
Method & \multicolumn{2}{c}{\emph{shapes_translation}} & 
         \multicolumn{2}{c}{\emph{shapes_6dof}}   & 
         \multicolumn{2}{c}{\emph{poster_6dof}}   & 
         \multicolumn{2}{c}{\emph{slider_depth}} \ 
\cmidrule{2-3} \cmidrule{4-5} \cmidrule{6-7} \cmidrule{8-9} 
& AOR & AR & AOR & AR & AOR & AR & AOR & AR\ 
\midrule
SiamFC\cite{bertinetto2016fully} & 0.812 & 0.940 & 0.835 & 0.968 & 0.830 & 0.956 & 0.909 & \textbf{1.000}       \ 
ECO\cite{danelljan2017eco}       & 0.823 & 0.943 & 0.847 & 0.969 & 0.846 & 0.960 & \textbf{0.947} & \textbf{1.000} \ 
SiamRPN++\cite{Li_2019_CVPR}     & 0.790 & 0.942 & 0.779 & 0.972 & 0.753 & 0.899 & 0.907 & \textbf{1.000}       \ 
ATOM\cite{Danelljan_2019_CVPR}   & 0.815 & 0.945 & 0.803 & 0.974 & 0.835 & 0.961 & 0.897 & \textbf{1.000}       \ 
%E-MS\cite{barranco2018real}      & 0.675 & 0.768 & 0.612 & 0.668 & 0.417 & 0.373 & 0.447 & 0.350  \ 
%RMRNet-TS                        & 0.491 & 0.564 & 0.467 & 0.509 & 0.504 & 0.558 & 0.814 & 0.993  \ 
%RMRNet                           & \textbf{0.836}& \textbf{0.951}& \textbf{0.866}& \textbf{0.980} &\textbf{0.859} &\textbf{0.962} & 0.915 & \textbf{1.000} \

\bottomrule
\end{tabular*}
\bigskip
\caption{Center-set first two data columns}
\begin{tabular}{1\textwidth}{@{\extracolsep{\fill}} l wc{\mylen}@{}wc{\mylen} {6}{c} }
\toprule
Method & \multicolumn{2}{c}{\emph{shapes_translation}} & 
         \multicolumn{2}{c}{\emph{shapes_6dof}}   & 
         \multicolumn{2}{c}{\emph{poster_6dof}}   & 
         \multicolumn{2}{c}{\emph{slider_depth}} \ 
\cmidrule{2-3} \cmidrule{4-5} \cmidrule{6-7} \cmidrule{8-9} 
& AOR & AR & AOR & AR & AOR & AR & AOR & AR\ 
\midrule
SiamFC\cite{bertinetto2016fully} & 0.812 & 0.940 & 0.835 & 0.968 & 0.830 & 0.956 & 0.909 & \textbf{1.000}       \ 
ECO\cite{danelljan2017eco}       & 0.823 & 0.943 & 0.847 & 0.969 & 0.846 & 0.960 & \textbf{0.947} & \textbf{1.000} \ 
SiamRPN++\cite{Li_2019_CVPR}     & 0.790 & 0.942 & 0.779 & 0.972 & 0.753 & 0.899 & 0.907 & \textbf{1.000}       \ 
ATOM\cite{Danelljan_2019_CVPR}   & 0.815 & 0.945 & 0.803 & 0.974 & 0.835 & 0.961 & 0.897 & \textbf{1.000}       \ 
%E-MS\cite{barranco2018real}      & 0.675 & 0.768 & 0.612 & 0.668 & 0.417 & 0.373 & 0.447 & 0.350  \ 
%RMRNet-TS                        & 0.491 & 0.564 & 0.467 & 0.509 & 0.504 & 0.558 & 0.814 & 0.993  \ 
%RMRNet                           & \textbf{0.836}& \textbf{0.951}& \textbf{0.866}& \textbf{0.980} &\textbf{0.859} &\textbf{0.962} & 0.915 & \textbf{1.000} \

\bottomrule
\end{tabular*}
\bigskip
\caption{Use abbreviation in header cell}
\begin{tabular}{\textwidth}{@{\extracolsep{\fill}} l {8}{c} }
\toprule
Method & \multicolumn{2}{c}{\emph{shapes_transl.}} & 
         \multicolumn{2}{c}{\emph{shapes_6dof}}   & 
         \multicolumn{2}{c}{\emph{poster_6dof}}   & 
         \multicolumn{2}{c}{\emph{slider_depth}} \ 
\cmidrule{2-3} \cmidrule{4-5} \cmidrule{6-7} \cmidrule{8-9} 
& AOR & AR & AOR & AR & AOR & AR & AOR & AR\ 
\midrule
SiamFC\cite{bertinetto2016fully} & 0.812 & 0.940 & 0.835 & 0.968 & 0.830 & 0.956 & 0.909 & \textbf{1.000}       \ 
ECO\cite{danelljan2017eco}       & 0.823 & 0.943 & 0.847 & 0.969 & 0.846 & 0.960 & \textbf{0.947} & \textbf{1.000} \ 
SiamRPN++\cite{Li_2019_CVPR}     & 0.790 & 0.942 & 0.779 & 0.972 & 0.753 & 0.899 & 0.907 & \textbf{1.000}       \ 
ATOM\cite{Danelljan_2019_CVPR}   & 0.815 & 0.945 & 0.803 & 0.974 & 0.835 & 0.961 & 0.897 & \textbf{1.000}       \ 
%E-MS\cite{barranco2018real}      & 0.675 & 0.768 & 0.612 & 0.668 & 0.417 & 0.373 & 0.447 & 0.350  \ 
%RMRNet-TS                        & 0.491 & 0.564 & 0.467 & 0.509 & 0.504 & 0.558 & 0.814 & 0.993  \ 
%RMRNet                           & \textbf{0.836}& \textbf{0.951}& \textbf{0.866}& \textbf{0.980} &\textbf{0.859} &\textbf{0.962} & 0.915 & \textbf{1.000} \
\bottomrule
\end{tabular*}
\bigskip
\caption{Use a smaller font size in header cell}
\begin{tabular}{1\textwidth}{@{\extracolsep{\fill}} l {8}{c} }
\toprule
Method & \multicolumn{2}{c}{\scriptsize\emph{shapes_translation}} & 
         \multicolumn{2}{c}{\emph{shapes_6dof}}   & 
         \multicolumn{2}{c}{\emph{poster_6dof}}   & 
         \multicolumn{2}{c}{\emph{slider_depth}} \ 
\cmidrule{2-3} \cmidrule{4-5} \cmidrule{6-7} \cmidrule{8-9} 
& AOR & AR & AOR & AR & AOR & AR & AOR & AR\ 
\midrule
SiamFC\cite{bertinetto2016fully} & 0.812 & 0.940 & 0.835 & 0.968 & 0.830 & 0.956 & 0.909 & \textbf{1.000}       \ 
ECO\cite{danelljan2017eco}       & 0.823 & 0.943 & 0.847 & 0.969 & 0.846 & 0.960 & \textbf{0.947} & \textbf{1.000} \ 
SiamRPN++\cite{Li_2019_CVPR}     & 0.790 & 0.942 & 0.779 & 0.972 & 0.753 & 0.899 & 0.907 & \textbf{1.000}       \ 
ATOM\cite{Danelljan_2019_CVPR}   & 0.815 & 0.945 & 0.803 & 0.974 & 0.835 & 0.961 & 0.897 & \textbf{1.000}       \ 
%E-MS\cite{barranco2018real}      & 0.675 & 0.768 & 0.612 & 0.668 & 0.417 & 0.373 & 0.447 & 0.350  \ 
%RMRNet-TS                        & 0.491 & 0.564 & 0.467 & 0.509 & 0.504 & 0.558 & 0.814 & 0.993  \ 
%RMRNet                           & \textbf{0.836}& \textbf{0.951}& \textbf{0.866}& \textbf{0.980} &\textbf{0.859} &\textbf{0.962} & 0.915 & \textbf{1.000} \
\bottomrule
\end{tabular*}
\end{table}
\end{document}

Sincerely Thanks! I have learned a lot from you. I finally choose the 'tabularray' package to solve the question for its convenience. — xueyinhualuo, Aug 22 '21 at 12:33

score 1 · Accepted Answer · answered Aug 22 '21 at 10:45

The new LaTeX3 package tabularray has an option hspan=even for distributing extra space evenly:

\documentclass{article}
\usepackage{tabularray}
\usepackage{caption}
\begin{document}
\begin{table}[!t]
    \centering
    \caption{Performance}
        \begin{tblr}{
          colspec = |c|c|c|c|c|c|c|c|c|,
          cell{1}{1} = {r=2}{c}, % multirow
          cell{1}{even} = {c=2}{c}, % multicolumn
          hspan = even, % distribute extra space evenly
          colsep = 5.5pt,
        }
        \hline
          Method & \emph{shapes_translation} & & \emph{shapes_6dof} & & \emph{poster_6dof} & & \emph{slider_depth} & \
        \cline{2-9}
                 & AOR & AR                     & AOR & AR              & AOR & AR              & AOR & AR \
        \hline
            SiamFC\cite{bertinetto2016fully}
                 & 0.812  & 0.940               & 0.835    & 0.968      & 0.830   & 0.956       & 0.909 & \textbf{1.000} \
        \hline
            ECO\cite{danelljan2017eco}
                 & 0.823  & 0.943 & 0.847  & 0.969 & 0.846   & 0.960  & \textbf{0.947}  & \textbf{1.000} \
        \hline
            SiamRPN++\cite{Li_2019_CVPR}
                 & 0.790  & 0.942  & 0.779  & 0.972 & 0.753  & 0.899  & 0.907 & \textbf{1.000} \
        \hline
            ATOM\cite{Danelljan_2019_CVPR}
                 & 0.815   & 0.945  & 0.803  & 0.974 & 0.835  & 0.961  & 0.897 & \textbf{1.000} \
        \hline
            E-MS\cite{barranco2018real}
                 & 0.675    & 0.768   & 0.612 & 0.668 & 0.417 & 0.373 & 0.447   & 0.350  \
        \hline
            RMRNet-TS 
                 & 0.491    & 0.564   & 0.467 & 0.509 & 0.504 & 0.558 & 0.814   & 0.993  \ \hline
            RMRNet
                 & \textbf{0.836} & \textbf{0.951} & \textbf{0.866} & \textbf{0.980} & \textbf{0.859} & \textbf{0.962} & 0.915   & \textbf{1.000}  \
        \hline
        \end{tblr}
\end{table}
\end{document}

Thanks for your answer. I am preparing my thesis. I have tried the package. It seems that the template does not support LaTeX3. — xueyinhualuo, Aug 22 '21 at 11:52
@xueyinhualuo LaTeX3 is already there. You only need to update your TeXlive or MikTeX to the latest and add \usepackage{tabularray} to your document. — L.J.R., Aug 22 '21 at 12:00
I got several errors and warnings (such as File `ninecolors.sty' not found. \begin{document}) after I put '\usepackage{tabularray}' into my template. I have correctly installed the package and TexLive 2021 is used. — xueyinhualuo, Aug 22 '21 at 12:11

Inappropriate column size when using \multicolumn

2 Answers2

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