Make enumeration label and text both flush left

enumitem

Using the enumitem package, I'd like to get list formatting that looks like this:

That is, I want top-level enumeration items as well as top-level text to be at the left margin along with the top-level enumeration label, and no newline if the item starts with a second-level enumeration. The closest I've managed to come is this:

\setlist[enumerate]{left=0pt .. \parindent}
\setlist[enumerate,1]{label={\bfseries{\arabic{section}.\arabic{enumi}.}}}
\setlist[enumerate,2]{label=(\alph{enumii})}
\setlist[enumerate,3]{label=(\roman{enumiii})}

which still sets the text of the item to the right of the label. Is there an easy way to do this?

Best Answer

enumitem's wide=0pt is what you're looking for here, together with a second-level enumerate set to align=left:

\documentclass{article}

\usepackage{enumitem,amsmath}

\setlist[enumerate,1]{label={\bfseries\arabic{section}.\arabic*.},wide=0pt}
\setlist[enumerate,2]{label=(\alph*),align=left}
\setlist[enumerate,3]{label=(\roman*)}

\begin{document}

\section{A section}

\begin{enumerate}
  \item
  \begin{enumerate}
    \item
    We compute as follows:
    \begin{align*}
      (xz \pm nyw)^2 + n (xw \mp yz)^2 &= x^2 z^2 \pm 2 nxyzw + n^2 y^2 w^2 + n x^2 w^2 \mp 2 nxwyz + n y^2 z^2 \\
                                       &= x^2 z^2 + n^2 y^2 w^2 + n x^2 w^2 + n y^2 z^2                         \\
           (x^2 + n y^2) (z^2 + n w^2) &= x^2 z^2 + n x^2 w^2 + n y^2 z^2 + n^2 y^2 w^2
    \end{align*}
    Hence, the right-hand sides are equal, proving (1.6).
    
    \item
    $(a x^2 + c y^2) (a z^2 + c w^2) = (axz \pm cyw)^2 + ac (xw \mp yz)^2$.
  \end{enumerate}
  
  \item This exercise forms part of an \verb|enumerate| and wraps around to the second line of text.
  \begin{enumerate}
    \item
    Item~1
    
    \item
    Item~2
    \begin{enumerate}
      \item
      What is the indentation?
    \end{enumerate}
  \end{enumerate}
\end{enumerate}

\end{document}

Related Solutions

[Tex/LaTex] How to make enumerate items align at left margin

Here is a way to do it using references, and consequently at least two compilations. It requires using labelwidth rather than widest. First, some background...

The obvious motivation behind itemize and description providing solutions to this without problem is because the former (itemize) uses a single-element (symbol) to denote list items, all of which have the same width (by default). Overriding this default to anything other than a single-element (symbol) will have misaligned items, or item labels protruding margin lines:

\begin{itemize}
  \item An item
  \item[qwerty] An item
  \item An item
\end{itemize}

This is due to the left-aligned nature of the itemized bullets. Another motivation is because lists are typeset "on the fly" and even allow for page breaks between items. So, in order to know the widest item at the start, the entire enumerate environment body would have to be read in memory/parsed before determining the widest, and then typeset - not the case by default. The latter (description) works because it uses a right-aligned approach to typesetting the itemized bullets and has a paragraph-style typesetting of the label and item contents by default.

The solution using enumerate requires setting the following enumitem options for a list:

labelindent=0pt: to have a flush left margin;
labelwidth=\widthof{\ref{last-item}}: this requires the calc package that measures the width of \ref{last-item} where last-item is a label set for the last item in your list;
label=\arabic*.: labels will be arabic, followed by a period .;
itemindent=1em: separation/space between label and item; and
leftmargin=!: automatically calculate what the leftmargin should be based on the provided parameters above (this is new to version 3.0 of enumitem).

Here is a minimal example highlighting the result:

\documentclass{article}
\usepackage{enumitem}% http://ctan.org/pkg/enumitem
\usepackage{calc}% http://ctan.org/pkg/calc
\begin{document}
\noindent Just enough text to make the line break so we get to see a second line.
\begin{enumerate}[labelindent=0pt,labelwidth=\widthof{\ref{last-item}},label=\arabic*.,itemindent=1em,leftmargin=!]
  \item An item
  \item An item
  \item An item \addtocounter{enumi}{9997}
  \item An item \label{last-item}
\end{enumerate}
Just enough text to make the line break so we get to see a second line.
\end{document}

Dynamically-aligned enumerate label

[Tex/LaTex] Custom enumerate margin with enumitem

Here is a solution to your problem, I think. This is quite an awful looking format. The tricky part is getting the indent of the first item of an embedded second level list. This bit of hackery (appropriately called \trickindent) is due to egreg.

\documentclass{article}
\usepackage{enumitem}
\usepackage{kantlipsum}
\setlist[enumerate]{nosep,itemindent=3.5em}
\newcommand{\trickindent}{%
  \let\normalitem\item
  \def\item{%
    \itemindent=0pt
    \normalitem
    \itemindent=3.5em
    \let\item\normalitem}%
}
\begin{document}
\begin{enumerate}
\item\kant*[1]
\begin{enumerate}
\item\kant*[4]
\end{enumerate}
\item\begin{enumerate}[before=\trickindent]
  \item\kant*[2]
  \item\kant*[3]
\end{enumerate}
\end{enumerate}
\end{document}

output of code

Best Answer

Related Solutions

[Tex/LaTex] How to make enumerate items align at left margin

[Tex/LaTex] Custom enumerate margin with enumitem

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