去掉桌子的一角

Question

我使用以下内容绘制了一个表格：

\begin{table}[hbt]
\begin{center}
\begin{tabular}{| l | l | c | c |}
    \cline{2-4}
    \hhline{~---} & \multicolumn{3}{c|}{Examples}\\
    \hhline{~---}
    & description & $M$ & ${\bf{u}}$\\
    \hline
    translation & through vector $\left(\begin{smallmatrix} 6 \\ 7 \end{smallmatrix}\right)$ & $\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}$ & $\begin{pmatrix} 6 \\ 7 \end{pmatrix}$ \\
    \hline
    reflection & in line $x = 2$ & $\begin{pmatrix} -1 & 0 \\ 0 & 1 \end{pmatrix}$ & $\begin{pmatrix} 4 \\ 0 \end{pmatrix}$ \\
    \hline
    rotation & about ${\bf{0}}$ through $\pi$ radians & $\begin{pmatrix} -1 & 0 \\ 0 & -1 \end{pmatrix}$ & $\begin{pmatrix} 0 \\ 0 \end{pmatrix}$ \\
    \hline
    glide reflection & in line $y = x$, then through $\left(\begin{smallmatrix} 1 \\ 1 \end{smallmatrix}\right)$ & $\begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}$ & $\begin{pmatrix} 1 \\ 1 \end{pmatrix}$ \\
    \hline
\end{tabular}
\caption{Examples of Euclidean Transformations}
\label{tab1}
\end{center}
\end{table}

如何删除左上角的垂直线？

Answer 1

为此使用两个\multicolumn{1}{c|} 。我借此机会改进了您的表格，使其垂直线和水平线整齐相交，并在行中添加了一些填充，并附带了包装makecell。最后，我将最后一行的前两个单元格更改为两行单元格：

\documentclass{article}
\usepackage{mathtools, nccmath, hhline}
\usepackage{makecell}
\setcellgapes{3pt}
\begin{document}

\begin{table}[hbt]
\centering\makegapedcells
\begin{tabular}{|r | l | c | c |}
    \cline{2-4}
    \hhline{~|---|} \multicolumn{1}{c |}{}& \multicolumn{3}{c|}{Examples}\\
    \hhline{~|---|}
    \multicolumn{1}{c |}{}& description & $M$ & ${\bf{u}}$\\
    \hhline{|----|}
    translation & through vector $\left(\begin{smallmatrix} 6 \\ 7 \end{smallmatrix}\right)$ & $\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}$ & $\begin{pmatrix} 6 \\ 7 \end{pmatrix}$ \\
    \hhline{|----|}
    reflection & in line $x = 2$ & $\begin{pmatrix} -1 & 0 \\ 0 & 1 \end{pmatrix}$ & $\begin{pmatrix} 4 \\ 0 \end{pmatrix}$ \\
    \hhline{|----|}
    rotation & about ${\bf{0}}$ through $\pi$ radians & $\begin{pmatrix} -1 & 0 \\ 0 & -1 \end{pmatrix}$ & $\begin{pmatrix} 0 \\ 0 \end{pmatrix}$ \\
    \hhline{|----|}
    \makecell[l]{glide reflection\\~} &\makecell[l]{ in line $y = x$,\\ then through $\left(\begin{smallmatrix} 1 \\ 1 \end{smallmatrix}\right)$} & $\begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}$ & $\begin{pmatrix} 1 \\ 1 \end{pmatrix}$ \\
    \hhline{|----|}
\end{tabular}
\caption{Examples of Euclidean Transformations}
\label{tab1}
\end{table}

\end{document} 

Answer 2

\documentclass{article}
\usepackage{hhline}
\usepackage{mathtools}

\begin{document}
    \begin{table}[hbt]
\centering
\begin{tabular}{| l | l | c | c |}
    \cline{2-4}
    \hhline{~---} 
\multicolumn{1}{c|}{}% <-- added
    & \multicolumn{3}{c|}{Examples}\\
    \hhline{~---}
\multicolumn{1}{c|}{}% <-- added
    & description & $M$ & ${\bf{u}}$\\
    \hline
    translation & through vector $\left(\begin{smallmatrix} 6 \\ 7 \end{smallmatrix}\right)$ & $\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}$ & $\begin{pmatrix} 6 \\ 7 \end{pmatrix}$ \\
    \hline
    reflection & in line $x = 2$ & $\begin{pmatrix} -1 & 0 \\ 0 & 1 \end{pmatrix}$ & $\begin{pmatrix} 4 \\ 0 \end{pmatrix}$ \\
    \hline
    rotation & about ${\bf{0}}$ through $\pi$ radians & $\begin{pmatrix} -1 & 0 \\ 0 & -1 \end{pmatrix}$ & $\begin{pmatrix} 0 \\ 0 \end{pmatrix}$ \\
    \hline
    glide reflection & in line $y = x$, then through $\left(\begin{smallmatrix} 1 \\ 1 \end{smallmatrix}\right)$ & $\begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}$ & $\begin{pmatrix} 1 \\ 1 \end{pmatrix}$ \\
    \hline
\end{tabular}
\caption{Examples of Euclidean Transformations}
\label{tab1}
    \end{table}
\end{document}