Re-use code like figures and paragraphs in other documents

Question

I was wondering if there is a way in which I can reuse the code, for example one figure, that is written in one file into another file.

I want to use something similar to xr package that allows you to reuse the labels references from one file into another. But I want to use it in the figures code or in entire paragraphs.

To illustrate what I need to do lets assume I have a file A.tex in which I already define a figure. And I have another file B.tex. And now I want to use the same definition of the figure in B. However, I want to "link" to the figure code in A; because if I do some change in A, I don't have to copy and paste everything in B again. Also, I want to do this with paragraphs. It is kind of quoting the previous file.

Is it possible using LaTeX? What do you suggest me to do?

Edit:

I need to do this "copy & paste" to include text and figures from the main document, into a second one. This references should have the same number of figures, and same bibliography reference, etc. That's why I say that I need something similar to xr package.

I tried using \include and \input to see if it was readable. However, I run into another problem. The number of figures and references are not maintained in the second document. The \include creates new numbers for each document. But I need to maintain the same as the original document.

Is there a way to do this "copy & paste" automatically?

Answer 1

You can move the code that needs to be used in multiple documents to a separate .tex file. Then, in each document write

\input{something.tex}

or just

\input{something}

in the exact place where you would want to include the .tex file. \input will cause TeX to read the file and treat its content as if it was written directly instead of \input. If you know C or C++, then \input is very similar to the #include preprocessor directive.

Answer 2

You could put any code that wanted to re-use into your own package, and name it something like mypackage.sty, and then include it in the relevant documents using \usepackage{mypackage.sty}.

Below is a sample MWE:

mypackage.sty

\def\myfigure{\begin{figure}[!h]%
\centering%
\rule{30pt}{20pt}%
\end{figure}%
 }
 \def\myparagraph{%
 Your paragraph text goes here.%
 }

document.tex

 \documentclass{article}
 \usepackage{mypackage}

 \begin{document}

 hello world

 \myfigure

 \myparagraph
 \end{document}

Note that if you plan to use the mypackage.sty in documents that reside in different directories, you will have to put it in a place where TeX will know to look for it.

Answer 3

The standalone package is perfectly suited for this kind of task. As mentioned in About \include in LaTeX use the following for the figure:

\documentclass[preview=false]{standalone}

Then, where you need this figure you you \input the figure. A good example is provided here.

This also allows you to fine tune the figure and reuse it as desired. Here is an example. Save the following as Ellipse.tex:

\documentclass{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}

\coordinate (EllipseOrigin) at (0,0);
\newcommand*{\XRadius}{4.0}
\newcommand*{\YRadius}{3.0}

\draw [blue, thin, ->] (-5,0) -- (5,0) node [right] {$x$};
\draw [blue, thin, ->] (0,-4) -- (0,4) node [above] {$y$};

\draw [red, ultra thick]% Graph Ellipse
    (EllipseOrigin) ellipse [x radius=\XRadius,y radius=\YRadius];

\end{tikzpicture}
\end{document}

Then where you want to use this:

\documentclass{article}
\usepackage{standalone}
\usepackage{tikz}

\begin{document}
Here is the graph of an ellipse:

\input{Ellipse}
\end{document}

If you want the exact same content (same Figure numbers) you should consider using pdfpages:

\documentclass{article}
\usepackage{pdfpages}

\begin{document}
\includepdf{Ellipse}
\end{document}