44

I wanted to put a bit of space after an \hline in an array; the main suggestion floating round the Internet seems to be to use

\hline \\ [-1.5ex]

Unfortunately, this causes a gap in the line on the RHS of the array. A minimal example is:

\documentclass{article}
\begin{document}
$\begin{array}{|l|l|}%
\hline
& TEXT\\
\hline \\[-1.5ex]
&TEXT
\\\hline
\end{array}$
\end{document}

enter image description here

Any help would be much appreciated!

David Carlisle
  • 757,742
Mohan
  • 15,906
  • What are you after? Reducing the gap between lines in your array or increasing it? – Werner Jul 29 '12 at 13:21
  • Increasing it. The -1.5ex is just because a full line is too much white space. The method is from http://stackoverflow.com/questions/696157/latex-hline-spacing . – Mohan Jul 30 '12 at 23:33
  • 1
    For reference, if you want to add blank space (no borders) between two rows, see here. E.g. use \addlinespace from booktabs. – Albert Aug 29 '18 at 12:58

3 Answers3

50

Rather than fiddle with the properties of \hline, it's better -- in your case -- to provide typographic "struts": either a "top strut," which provides vertical spacing above the line on which it's placed, or a "bottom strut," which provides vertical spacing below the line on which it's placed. This idea is not original to me; it goes back (at least) to an article published by Claudio Beccari in TeX and TUG News in 1993. What's nifty about this approach is that one can place both a top strut and a bottom strut on a given line of an array or tabular environment.

The following MWE shows how this may be done. Note that I've switched from array to tabular in order to pare things down to the bare minimum; the vertical spacing issues related to \hline are the same for both environments.

enter image description here

\documentclass{article}
\usepackage{array}
% Define typographic struts, as suggested by Claudio Beccari
%   in an article in TeX and TUG News, Vol. 2, 1993.
\newcommand\Tstrut{\rule{0pt}{2.6ex}}         % = `top' strut
\newcommand\Bstrut{\rule[-0.9ex]{0pt}{0pt}}   % = `bottom' strut

\begin{document}
With struts on the left, without struts on the right:


\begin{tabular}[t]{|l|}
\hline
TEXT\Tstrut\Bstrut\ % top and bottom struts
\hline
TEXT\Tstrut\        % top strut only
TEXT\Bstrut\        % bottom strut only
\hline
\end{tabular}
\quad
\begin{tabular}[t]{|l|}
\hline
TEXT\ 
\hline
TEXT\

TEXT\

\hline
\end{tabular}
\end{document}
Mico
  • 506,678
  • Thanks! I've left some related comments on Werner's post... – Mohan Jul 30 '12 at 23:31
  • @Mohan - You mention (in a comment left on Werner's answer) that your tabular environments are generated by some program (Stata, maybe?). If so, can't you set up the program to insert a \Tstrut instruction (rather than something like \\[1ex], say) automatically after every \hline? Just a thought. – Mico Jul 31 '12 at 00:25
  • The arrays are generated by some Haskell code I've written. It's not inserting the strut commands that's tricky... it's the fact that the heights of entries might vary. Unless I've misunderstood something, if a particular entry is taller than a Tstrut, the strut will have no effect. Is that right? – Mohan Jul 31 '12 at 11:37
  • @Mohan - It depends where the \Tstrut instruction is inserted. If it's inserted on the baseline, you're correct in assuming that it won't have an effect on stuff that's tall than Tstrut. Assuming that what's being typeset is some mathematical expression with superscripts, could you modify the Haskell code to insert a \Tstrut inside the superscript's argument? – Mico Jul 31 '12 at 11:45
  • thanks again for all the advice! It's not in fact, a superscript; it's a representation used in linguistics, and you can have tables nested inside tables (to arbitrary depth). But when I was playing around I found that the padding I'm putting around tables can be made sufficient to distance nested tables from the hline, which is good enough. Thanks for all the help!

    (Just in case you're interested, the result is at http://s14.postimage.org/5cy6abt7j/derivation_images_80.png .)

     – Mohan Jul 31 '12 at 21:10
  • 2
    One more thing that I got bitten with is that the displayed table in the answer above has extra white space at the end when using strut compared to without. This can be resolved by changing TEXT \Tstrut to TEXT\Tstrut (i.e. taking away the space between text and \Tstrut). – Fanchen Bao Nov 28 '20 at 00:52
  • 1
    @FanchenBao - Many thanks for noticing and pointing the issue caused by the space I had left before \Tstrut and \Bstrut in the first tabular environment. I've gone ahead and updated the MWE -- both the code and the associated screenshot. – Mico Nov 28 '20 at 08:07
14

On a case-by-case basis you can insert a vertical strut (zero-width, vertical rule/object) to push the row contents away from others. Here's a small example:

enter image description here

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\[
  \begin{array}{|l|l|}%
    \hline
    & \text{Text} \\
    \hline
    \rule{0pt}{1.5\normalbaselineskip} & \text{Text} \\
    \hline
  \end{array}
\]
\end{document}

I've inserted a vertical strut of height 1.5\normalbaselineskip which is 18pt in the above example, any length exceeding the about 70% of the baseline skip would work. For more information on column and/row padding, see Column padding in tables.

Note that I've used amsmath to supply the \text command for setting text in math mode. Even though this is just a simple example and using \mbox would also suffice, amsmath also provides other functionality that is well worth using.

If you wish to insert a fixed amount (say) <len> between two rows, you can insert a blank row (with the appropriate number of column alignments & to provide correct vertical rule placement) and use a row skip of the form \\[\dimexpr-\normalbaselineskip+<len>]. This would jump "back" a length of \normalbaselineskip - the baseline distance between rows - and jump "forward" by <len> - the required gap. Here's a small example:

enter image description here

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\[
  \begin{array}[t]{|l|l|}%
    \hline
    & \text{Normal} \\
    \hline
    & \text{Text} \\
    \hline
  \end{array} \quad
  \begin{array}[t]{|l|l|}%
    \hline
    & \texttt{0pt} \\
    \hline
    & \\[-\normalbaselineskip]
    & \text{Text} \\
    \hline
  \end{array} \quad
  \begin{array}[t]{|l|l|}%
    \hline
    & \texttt{2pt} \\
    \hline
    & \\[\dimexpr-\normalbaselineskip+2pt]
    & \text{Text} \\
    \hline
  \end{array} \quad
  \begin{array}[t]{|l|l|}%
    \hline
    & \texttt{1em} \\
    \hline
    & \\[\dimexpr-\normalbaselineskip+1em]
    & \text{Text} \\
    \hline
  \end{array} \quad
  \begin{array}[t]{|l|l|}%
    \hline
    & \texttt{3pc} \\
    \hline
    & \\[\dimexpr-\normalbaselineskip+3pc]
    & \text{Text} \\
    \hline
  \end{array}
\]
\end{document}
Moriambar
  • 11,466
Werner
  • 603,163
  • Thanks! There is one difficulty with this approach, which is that I'm automatically generating my LaTeX code in a program. So I can't tune the height on a case-by-case basis. I will experiment with putting in a constant-height strut, but what I really want to do is put a fixed amount of space between the hline and whatever comes after it, regardless of the height of the latter.

    Maybe I can wrap whatever comes after the hline in some kind of vertical box, with a strut placed above it? It's a bit fiddly, but it would probably work...

     – Mohan Jul 30 '12 at 23:28
  • @Mohan: I've updated my answer with a possibility that might work for you. Give some feedback if it doesn't. – Werner Aug 01 '12 at 15:16
  • "with the appropriate number of column alignments & to provide correct vertical rule placement" --- ah! That's what I was missing. Thank you very much. (Output is now also satisfactory, though I used other means.) – Mohan Aug 01 '12 at 17:22
1

Just add a (missing) ampersand, otherwise the last cell and its border are not created:

\documentclass{article}
\begin{document}
$\begin{array}{|l|l|}%
\hline
& TEXT\\
\hline
& % <<<< here
\\[-1.5ex]
&TEXT
\\\hline
\end{array}$
\end{document}
Alexey
  • 2,099