[Tex/LaTex] one-column multicol environment

multicol

I'm writing some xsl that takes xml source and outputs a .tex file. The source has an element that is meant to frequently become a multicols environment in the .tex output, and it has a cols attribute to specify how many columns there are.

I'd like the default to be one column if no cols attribute has been specified. But it appears that \begin{multicols}{1} still produces two-column output. I could write the xsl in a casewise way and skip the multicols environment altogether when cols is not specified (or is specified as 1), but for the sake of consistency I'd prefer not to.

Is there any LaTeX way to get the multicols environment to produce one-column output?

Best Answer

This solution is inspired by Werner's, but it supports the optional argument to \begin{multicols} and, more importantly, doesn't collect the whole contents in a single swoop, which is best to avoid, if possible. It also doesn't require changing the environment's name.

\documentclass{article}
\usepackage{multicol,lipsum,xparse}

\let\multicolmulticols\multicols
\let\endmulticolmulticols\endmulticols

\RenewDocumentEnvironment{multicols}{mO{}}
 {%
  \ifnum#1=1
    #2%
  \else % More than 1 column
    \multicolmulticols{#1}[#2]
  \fi
 }
 {%
  \ifnum#1=1
  \else % More than 1 column
    \endmulticolmulticols
  \fi
 }

\begin{document}

\begin{multicols}{2}[\section{Title in single column}]
\lipsum[1-2]
\end{multicols}

\begin{multicols}{1}
\lipsum[1-2]
\end{multicols}

\end{document}

enter image description here

Related Solutions

[Tex/LaTex] Footnotes layout in multicols environment

There are a number of good reasons why it is impossible to provide the layout you are looking for with multicols. Two important ones are:

As the name implies the code is supposed to support different column numbers on the same page. Now how wide should a footnote be? Full text width is ugly, but so is any other width, if it doesn't fit with the rest of column setup. Even if the spec would be reduced be just "one and two columns with balancing" it would still be ugly if you have, say, a single footnote (in twocolumn width) but the bottom of your page ends up being one-column.
Technically, multicols works by collecting a page worth of material and then splitting off the columns (and in case of balancing at the end potentially retrying many (hundred) scenarios to find the best balancing solution). Now this works by using \vsplit and \vsplit is keeping footnote material inside the boxes. So by using this approach you can't use the footnote material as poart of the column itself (or taking part of the balancing). Now it is possible, of course, to use a different approach involving a collection of output routines that do all this kind of work on the main vertical list rather than safely with already gathered material in boxes. However, it would be a good factor more complicated and as a result really complex output routines typically limit themselves to solving restricted problems.

Now TeX is Turing complete as you mentioned in a comment, but this isn't going to help you much initially. It doesn't mean that it is feasible to program each and everything in TeX and even if it is possible you might end up dropping all or most of the functionality that TeX offers in one area and reprogram it in a fairly inefficient way yourself just to get over built-in limitations. Until quite recently the biggest hurdle was that doing that would also mean the processing would end up being incredibly slow or hit memory limits.

That situation has improved a lot in the last years and this is one of the reasons why it is now possible to come up with a programming framework (like expl3) that provides that basis for expanding TeX's abilities within TeX. When multicols was originally written it would have been impossible to envision that one implements a full blown regular expression parser in TeX (not technically but realistically) now we have one in expl3.

Bottom line, the design of TeX was made for single column documents, and anything that goes a lot beyond that was pretty much either impossible or only possible in restricted scenarios.

Nowadays, one could do better and we do have a different page design concept in the drawer that does offer what you are looking for. The catch is, it is not ready. Its proto-type is already from 2000, but back then it was still utopia, because of the speed restrictions it imposed.

That has changed, so now something like expl3 is a platform that can be (and is) used for real, and we are currently in the process of revising the code and ideas from the end of the last century. Now this sound awfully old, doesn't it? But fact is, for current LaTeX multicol is still around as "the" solution so ... there is some reason for that.

One column in multicol environment without break

I assume, that text in your document is in one column and that you like to have some lists in two (or more) columns. If I'm right, than in your document example you only need to remove {multicols}{1} environment.

Edit: Package memoir doesn't support continued numbering in consecutive enumerate lists (as far as I know). However it can be simple done by use of the enumitem packages as is done in the corrected MWE below:

\documentclass{memoir}
\usepackage{multicol}
\usepackage{enumitem}

\begin{document}

\begin{multicols}{2}
\begin{enumerate}[series=twocolumn]
    \item Two columns content
    \item Two columns content
    \item Two columns content
    \item Two columns content
    \item Two columns content
    \item Two columns content
    \item Two columns content
\end{enumerate}
\end{multicols}

\begin{enumerate}[resume*=twocolumn]
    \item This item should spanned in one column to look better
    \item This item also should spanned in one column to look better
    \item Again an item to be spanned in one column
    \item Again an item to be spanned in one column
    \item Again an item to be spanned in one column
\end{enumerate}

\end{document}

Best Answer

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[Tex/LaTex] Footnotes layout in multicols environment

One column in multicol environment without break

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