抑制數組上方和下方的垂直空間？

Question

環境array使用\arraystretch（並且\extrarowheight如果array加載了包）在array.此外，此垂直空間會新增在第一行上方和最後一行下方。

有沒有辦法抑制第一行上方和最後一行下方的空間，同時仍保留行間空間array？

myarray使用和mysolidarray（設定\arraystretch為）比較輸出，0如以下程式碼所定義。我正在尋找介於兩者之間的東西。

\documentclass{standalone}
\usepackage{array}
\usepackage{amsmath}

\newenvironment{myarray}%
  {\begin{array}[t]{@{}l@{}}}%
  {\end{array}}

\newenvironment{mysolidarray}%
  {%
    \def\arraystretch{0}%
    \begin{array}[t]{@{}l@{}}
  }%
  {\end{array}}

\begin{document}
\fboxsep=0pt
\begin{tabular}{l}
\verb|$P + Q$|: \fbox{$P + Q$}
\\
\verb|myarray|:
\fbox{$
  \begin{myarray}
    P + Q
  \end{myarray}
$}
\fbox{$
  \begin{myarray}
    P + {} \\ Q
  \end{myarray}
$}
\\
\verb|mysolidarray|:
\fbox{$
  \begin{mysolidarray}
    P + Q
  \end{mysolidarray}
$}
\fbox{$
  \begin{mysolidarray}
    P + {} \\ Q
  \end{mysolidarray}
$}
\end{tabular}
\end{document}

Answer 1

您可以測量陣列並將其排版兩次，首先取得第一行的高度，然後取得最後一行的深度。

\documentclass{article}
\usepackage{array}
\usepackage{environ}

\makeatletter
\NewEnviron{mysolidarray}[1]{%
  \begingroup
  \def\arraystretch{0}%
  \extrarowheight=\z@
  \sbox\z@{$\begin{array}[t]{#1}\BODY\end{array}$}%
  \sbox\tw@{$\begin{array}[b]{#1}\BODY\end{array}$}%
  \expandafter\endgroup\expandafter
  \firstlineheight\the\ht\expandafter\z@\expandafter
  \lastlinedepth\the\dp\tw@\relax
  \sbox{\solidarraybox}{$\begin{array}[t]{#1}\BODY\end{array}\m@th$}
  \ht\solidarraybox=\firstlineheight
  \dp\solidarraybox=\dimexpr\dp\solidarraybox-\dp\@arstrutbox+\lastlinedepth\relax
  \box\solidarraybox
}
\makeatother
\newdimen\firstlineheight
\newdimen\lastlinedepth
\newsavebox{\solidarraybox}

\begin{document}
\fboxsep=0pt 
\begin{tabular}{lll}
\verb|$P + Q$| & \fbox{$P + Q$}
\\
\verb|array|&
\fbox{$
  \begin{array}[t]{@{}l@{}}
    P + Q
  \end{array}
$}
\fbox{$
  \begin{array}[t]{@{}l@{}}
    P + {} \\ Q
  \end{array}
$}
&\extrarowheight=2pt
\fbox{$
  \begin{array}[t]{@{}l@{}}
    P + Q
  \end{array}
$}
\fbox{$
  \begin{array}[t]{@{}l@{}}
    P + {} \\ Q
  \end{array}
$}
\\
\verb|mysolidarray|&
\fbox{$
  \begin{mysolidarray}{@{}l@{}}
    P + Q
  \end{mysolidarray}
$}
\fbox{$
  \begin{mysolidarray}{@{}l@{}}
    P + {} \\ Q
  \end{mysolidarray}
$}
&\extrarowheight=2pt
\fbox{$
  \begin{mysolidarray}{@{}l@{}}
    P + Q
  \end{mysolidarray}
$}
\fbox{$
  \begin{mysolidarray}{@{}l@{}}
    P + {} \\ Q
  \end{mysolidarray}
$}
\end{tabular}
\end{document}

Answer 2

你有什麼意思嗎\setlength{\extrarowheight}{-1pt}？

\documentclass{standalone}
\usepackage{array}
\usepackage{amsmath}

\newenvironment{myarray}%
  { \setlength{\extrarowheight}{-1pt}
  \begin{array}[t]{@{}l@{}}}%
  {\end{array}}

\newenvironment{mysolidarray}%
  {%
    \def\arraystretch{0}%
    \begin{array}[t]{@{}l@{}}
  }%
  {\end{array}}

\begin{document}
\fboxsep=0pt
\begin{tabular}{l}
\verb|$P + Q$|: \fbox{$P + Q$}
\\
\verb|myarray|:
\fbox{$
  \begin{myarray}
    P + Q
  \end{myarray}
$}
\fbox{$
  \begin{myarray}
    P + {} \\ Q
  \end{myarray}
$}
\\
\verb|mysolidarray|:
\fbox{$
  \begin{mysolidarray}
    P + Q
  \end{mysolidarray}
$}
\fbox{$
  \begin{mysolidarray}
    P + {} \\ Q
  \end{mysolidarray}
$}
\end{tabular}
\end{document}

Answer 3

如果您不使用垂直規則（無論如何建議），您可以在 表格的第一個 \hline 之後和最後一個 \hline 之前使用\addlinespace[some value]from來完全控制：booktabs

\documentclass{article}
\usepackage{array, booktabs}
\usepackage{amsmath}
\usepackage[table]{xcolor}

\newenvironment{myarray}%
  {\begin{array}[t]{@{}l@{}}}%
  {\end{array}}

\newenvironment{mysolidarray}%
  {%
    \def\arraystretch{0}%
    \begin{array}[t]{@{}l@{}}
  }%
  {\end{array}}

\begin{document}
\fboxsep=0pt
\begin{tabular}{l}
\verb|$P + Q$|: \fbox{$P + Q$}
\\
\verb|myarray|:
\fbox{$
  \begin{myarray}
    P + Q
  \end{myarray}
$}
\fbox{$
  \begin{myarray}
    P + {} \\ Q
  \end{myarray}
$}
\\
\verb|mysolidarray|:
\fbox{$
  \begin{mysolidarray}
    P + Q
  \end{mysolidarray}
$}
\fbox{$
  \begin{mysolidarray}
    P + {} \\ Q
  \end{mysolidarray}
$}
\\[3ex]
\verb|othersolidarray|:
$
 \begin{array}{@{}l@{}}%
 \arrayrulecolor{red}
\hline\addlinespace[-1pt]
 P + Q \\ Q + P
\\
\addlinespace[-1.25pt]
\hline
 \end{array}
$
$
 \begin{array}{@{}l@{}}%
 \arrayrulecolor{red}
\hline\addlinespace[-1pt]
 P + {} \\ Q
\\
\addlinespace[-1.25pt]
\hline
 \end{array}
$
\end{tabular}

\end{document}