[Tex/LaTex] Enumerate: make labels and items aligned left within a theorem

#enumerateamsthmenumitemtheorems

Just what the title says: I want to make an enumerate list in which both the labels and items are aligned to the left. I can currently only get one or the other.

Minimal working example:

\documentclass{report}
\usepackage{amsthm}
\usepackage{enumitem}

\newtheoremstyle{theorem}
    {1em}{}{\itshape}{}{\bfseries}{}{1em}
    {\thmname{#1}\thmnumber{ #2}\thmnote{ (\normalfont\textit{#3})}}
\theoremstyle{theorem}
\newtheorem{thm}{Theorem}[section]

\begin{document}
\begin{thm}
\mbox{}\vspace{-0.175cm}
\begin{enumerate}[leftmargin=0.87cm, labelsep=0.325cm, 
    align=left, itemsep=-0.1cm, font=\normalfont, label=(\roman*)]

    \item First item.
    \item Second item.
    \item Third item.

\end{enumerate}
\end{thm}
\end{document}

I also would like a way to have the labels flush left with the margin, besides guessing and manually adjusting it each time.

It should look something like this:

(i)    First item.
(ii)   Second item.
(iii)  Third item. 
(iv)   Fourth item. 
etc.

Best Answer

Let enumitem figure out the leftmargin=* along with align=left:

enter image description here

As per you comments if you want it left aligned but with some indent, then you could define a custom alignment:

\SetLabelAlign{LeftAlignWithIndent}{\hspace*{2.0ex}\makebox[1.5em][l]{#1}}

and then using align=LeftAlignWithIndent you get:

enter image description here

Notes:

The showframe package was used just to show the page margins. It is not needed in your actual use case.

Code:

\documentclass{report}
\usepackage{amsthm}
\usepackage{enumitem}
\usepackage{showframe}

\SetLabelAlign{LeftAlignWithIndent}{\hspace*{1.0ex}\makebox[1.25em][l]{#1}}

\newtheoremstyle{theorem}
    {1em}{}{\itshape}{}{\bfseries}{}{1em}
    {\thmname{#1}\thmnumber{ #2}\thmnote{ (\normalfont\textit{#3})}}
\theoremstyle{theorem}
\newtheorem{thm}{Theorem}[section]

\begin{document}
\begin{thm}
\mbox{}\vspace{-0.175cm}
\begin{enumerate}[leftmargin=*, labelsep=*, 
    align=left, itemsep=-0.1cm, font=\normalfont, label=(\roman*)]

    \item First item.
    \item Second item.
    \item Third item.

\end{enumerate}
\end{thm}
    
\begin{thm}
\mbox{}\vspace{-0.175cm}
\begin{enumerate}[leftmargin=*, align=LeftAlignWithIndent, 
    itemsep=-0.1cm, font=\normalfont, label=(\roman*)]

    \item First item.
    \item Second item.
    \item Third item.

\end{enumerate}
\end{thm}
\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

Customized Enumerate Items in LaTeX

Without further information this is a starter...(I've not done the theorem environment around the enumeration)

The enumitem package is the key for easy customization of itemize/enumerate lists. It provides the means for use a starter value (start=0) and the label=.... option.

enumitem can be used together or as enumerate using the shortlabels option.

\documentclass{article}
\usepackage{enumerate}
\usepackage[shortlabels]{enumitem}

\begin{document}

% Traditional style
\begin{enumerate}[a)] 
\item This is
\item an easy
\item customization of standard enumerate
\end{enumerate}


\begin{enumerate}[start=0,label={(\bfseries R\arabic*):}]
\item This is
\item an easy
\item customization of enumerate
\end{enumerate}
\end{document}

enter image description here

Best Answer

Notes:

Code:

Related Solutions

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

Customized Enumerate Items in LaTeX

Related Question