How can I label marginpars or marginnotes to be able to refer to them?

Question

In a 200 page document I have 20-30 portions, 2-5 sentences long usually, scattered throughout that discuss something about statistics. My thought is to add a marginpar for each statistics portion.

My question is whether I can label each marginpar uniquely so that I am able to ref-er to it (and thus to the few sentences on statistics). [While tagging this question, marginnote appeared, and that might be an alternative to be labelled.)

EDIT: The reference to another question that shows how to number marginpar items, like footnotes are numbered sequentially, is very helpful, but doesn't explain how then to refer to a numbered marginpar later in the document.

If this is possible, it seems it will require a counter (need counter to refer to text that has been labeled). But being a beginner, I don't know whether the basic idea is a dead end let alone how to code it.

I am using R, RStudio, and the knitr package on Windows.

Answer 1

EDIT: As Dr. Manuel Kuehner mentioned in the comments, there is a package called marginnote, therefore the naming of the provided code is perhaps bad. Because of that I changed the \marginnote to \mymarginnote

This is a small setup, which allows what (I think) you want:

\documentclass[]{scrartcl}

\usepackage{lipsum}

\newcounter{marginnotenumber}[section]
\let\themarginbak\themarginnotenumber
\renewcommand{\themarginnotenumber}{\thesection.\themarginbak}
\newcommand{\mymarginnote}[2]{%
    \marginpar{%
        \refstepcounter{marginnotenumber}\label{#1}\themarginnotenumber: #2%
    }%
}

\begin{document}
\section{first section}
\lipsum[1-2]
\mymarginnote{not:mylab}{This is a marginnote}
\section{second section}
\lipsum[1-2]
also see marginnote \ref{not:mylab}.
\end{document}

In a book (containing chapters) you might want to define the counter like this:

\newcounter{marginnotenumber}[chapter]
\let\themarginbak\themarginnotenumber
\renewcommand{\themarginnotenumber}{\thechapter.\themarginbak}