Structuring Sources
Last updated on 2025-05-06 | Edit this page
Estimated time: 12 minutes
Overview
Questions
- How can we make it easier to manage large LaTeX projects?
- How can we reuse parts of our LaTeX document in other documents?
- How can we structure our LaTeX project?
Objectives
- Learn how to use commands to include other files in your LaTeX document
- Restructure a LaTeX project to use multiple files
Project Structure
So far, we’ve been putting all of our LaTeX code into a single document. This is fine for small projects, but even with what we have here so far, you might have started to feel like things are getting a little unwieldy and hard to manage.
One of the great things we can do with LaTeX is break our document up into smaller “sources”, which allows us to work on each part of the document separately. You can imagine this might be helpful when working on a large document with multiple chapters, where each chapter is a separate file. You might also find this useful when you intend to reuse parts of your document in other documents, like title pages, tables of contents, or lists of figures.
This also helps with collaboration, as multiple people can work on different parts of the document at the same time without having to worry about conflicts.
Commands
There are two important commands to know when working with multiple sources:
\input{filename}\include{filename}
The \input{filename} command will include the contents
of the file filename.tex at the point where the command is
called as though it was typed directly into the main document. This can
be useful for things that are not, for example, separate chapters, but
rather things like a title page, a table of contents, or a list of
figures.
The \include{filename} command will do the same thing,
but it will also start a new page before including the file. This is
useful for including separate chapters or sections of your document.
When you use \include{filename} you can also use
\includeonly{filename1,filename2} in your preamble. This
will then only insert the file mentioned but respect all other files
regarding e.g. pagenumber, references etc.
Input Example
Let’s try out using the \input{filename} command. We’ll
create a new file called input_example.tex in our project
directory with the following contents:
LATEX
\cmd{Input} is useful for including things as if they were typed directly into the main document.
Things like commands don't have to be defined in the included file, as long as they are defined in
the main document.Then, in our main.tex document, let’s add the following
section:
When we compile our document, we should see the contents of
input_example.tex included in our main document.
Include Example
Let’s try out using the \include{filename} command.
We’ll create a new file called include_example.tex in our
project directory with the following contents:
LATEX
\cmd{Include} is useful for including things as if they were typed directly into the main document,
but it will also start a new page before including the file.Then, in our main.tex document, let’s add the following
section:
When we compile our document, we should see the contents of
include_example.tex, however this time the content will
have included a new page before the content.
Callout
Another important thing to note about the
\include{filename} command is that it cannot contain
another \include{} command - this will result in an
error.
You can, however, use \input{} inside an
\include{} command or an \input{} command
inside another \input{} command.
Updating Our Project
Now that we’ve seen how to use the \input{filename} and
\include{filename} commands, let’s refactor our project to
use them. We’ll take each section and put it in it’s own file, then
include the files in our main.tex document. This will main
our main document easier to read and manage, while separating out the
content into more manageable pieces.
Let’s also organize our files a little bit. Instead of putting everything in the “root” directory of this project, we’ll create a folder called “content” and put our section files in there.
Separating Our Sections
Let’s make files in our “content” directory for each of our sections:
content/sections.texcontent/lists.texcontent/graphics.texcontent/tables.texcontent/cross-references.texcontent/mathematics.texcontent/fonts-and-spacing.texcontent/reference-databases.tex
We’ll move the content from each section into the corresponding file.
content/lists.tex
LATEX
\section{Lists}
There are two types of lists: ordered and unordered.
\subsection{Ordered}
Ordered lists do not have numbers associated with each item.
\begin{enumerate}
\item Item 1
\item Item 2
\item Item 3
\end{enumerate}
\subsection{Unordered}
Unordered lists are just a series of items preceded by a marker.
\begin{itemize}
\item Item 1
\item Item 2
\item Item 3
\end{itemize}
\end{document}content/graphics.tex
LATEX
\section{Graphics}
We can include \kw{images} in our document using the \cmd{graphicx} package, which lets us use the
\cmd{includegraphics} command.
\includegraphics{figures/example-image.png}
\subsection{Small Image}
We can pass parameters to the \cmd{includegraphics} command to adjust the appearance of the image.
\includegraphics[height=2cm]{figures/example-image.png}
Other possible options include:
\begin{itemize}
\item width: the width of the image
\item scale: the scaling factor of the image
\item angle: the angle of rotation of the image
\item clip: whether to clip the image to its bounding box
\item trim: trim the image by a specified amount
\item draft: display a box instead of the image
\end{itemize}
\subsection{Centered Image}
By placing the \cmd{includegraphics} command inside a center environment, we can center the
image on the page.
\begin{center}
\includegraphics[height=2cm]{figures/example-image.png}
\end{center}
\subsection{Floating Image}
\kw{Floating images} can move around the page as text is added or removed. We can use the
\cmd{figure}environment to create a floating image.
\begin{figure}[ht]
\centering
\includegraphics[height=2cm]{figures/example-image.png}
\end{figure}
Control the position of a floating image by passing paratmeters to the \cmd{figure} environment:
\begin{itemize}
\item h: Place the float "here" (where it appears in the code)
\item t: Place the float at the "top" of the page
\item b: Place the float at the "bottom" of the page
\item p: Place the float on a "page" by itself
\end{itemize}
\subsection{Caption}
We can add a \kw{caption} to our floating image by using the \cmd{caption} command inside of the
\cmd{figure} environment.
\begin{figure}[h]
\centering
\includegraphics[height=2cm]{figures/example-image.png}
\caption{This is a caption for our image.}
\end{figure}content/tables.tex
LATEX
\section{Tables}
\kw{Tables} are defined using the \cmd{tabular} environment.
\input{tables/basic-table}
\subsection{Tables with Horizontal Lines}
We can use the \cmd{\textbackslash toprule}, \cmd{\textbackslash midrule}, and
\cmd{\textbackslash bottomrule} commands from the \cmd{booktabs} package to create horizontal
lines in our table.
\input{tables/table-with-horizontal-lines}
\subsection{Partial Horizontal Lines}
The \cmd{\textbackslash cmidrule} command can be used to create partial horizontal lines in a
table. The command accepts the arguments {number-number}, where the first number is the column to
start the line and last number is the column to end the line.
\input{tables/table-with-partial-horizontal-lines}
\subsection{Merging Cells}
Merge cells horizontally using the \cmd{\textbackslash multicolumn} command. This command takes
three arguments:
\begin{itemize}
\item The number of cells which should be merged
\item The alignment of the merged cell (l, c, or r)
\item The contents of the merged cell
\end{itemize}
\input{tables/table-with-merged-cells}content/cross-references.tex
LATEX
\section{Cross References}
\label{sec:cross-references}
\subsection{Material for the Introduction}
In this section, we introduce two new concepts:
\begin{tabular}{cp{9cm}}
Command & Description \\
\toprule
\kw{label} & Marks a spot in the document \\
\kw{ref} & Refers to a marked spot in the document \\
\bottomrule
\label{tab:cross-reference-commands}
\end{tabular}
We can \kw{refer} to the section with the \cmd{ref} command, like this: \ref{sec:cross-references}.
We can likewise refer to the table like this: \ref{tab:cross-reference-commands}.content/mathematics.tex
LATEX
\section{Mathematics}
There are two kinds of math mode in LaTeX: inline and display. Inline math mode is marked with
a pair of dollar signs, whereas display math mode is marked with a pair of square brackets.
\subsection{Inline Math Mode}
The Pythagorean theorem is $a^2 + b^2 = c^2$.
\subsection{Display Math Mode}
The Fourier Transform is defined as:
\[
\hat{f}(\xi) = \int_{-\infty}^\infty f(x) e^{-2\pi i \xi x} \, dx
\]
Where:
\begin{itemize}
\item \( f(x) \) is the function we are transforming,
\item \( \hat{f}(\xi) \) is the Fourier Transform of \( f(x) \),
\item \( \xi \) is the frequency variable,
\item \( i \) is the imaginary unit.
\end{itemize}
\subsection{Math in Environments}
The quadratic formula is:
\begin{equation}
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
\label{eq:quadratic}
\end{equation}
This will allow us to refer to the equation later in the document with \cmd{ref} like this:
Refer to Equation \ref{eq:quadratic}.
\subsection{The `amsmath` Package}
Solve the following recurrence for $ n,k\geq 0 $:
\[
Q_{n,0} = 1 \quad Q_{0,k} = [k=0];
\]
\[
Q_{n,k} = Q_{n-1,k}+Q_{n-1,k-1}+\binom{n}{k}, \quad\text{for $n$, $k>0$.}
\]content/reference-databases.tex
LATEX
\section{Reference Databases}
One of the best features of LaTeX when writing academic documents is the ability to easily and
confidently \kw{cite references}.
We can cite the article by Thomas (e.g. with `\textbackslash autocite\{Thomas2008\}`) and it will show up in the references.
You should see that the citation appears in the text (`(Thomas et al. 2008)`), and the reference
now appears at the end of the document. \cmd{\textbackslash autocite} is a command that automatically chooses the
citation style for you.
Some additional commands that are available in `biblatex`:
\begin{itemize}
\item `\textbackslash cite\{key\}` or `\textbackslash cite\{key1, key2\}`: Cite the reference with the given key
\item `\textbackslash cites\{key1\}\{key2\}\{key-n\}`: Cite multiple references.
\item `\textbackslash usepackage\{\}\textbackslash parentcite\{key\}`: Cite the parent reference of the given key.
\item `\textbackslash autocite\{key\}`: Automatically choose the citation style.
\item `\textbackslash smartcite\{key\}`: Automatically choose the citation style, but with more control.
\item `\textbackslash footcite\{key\}`: Cite the reference in a footnote.
\end{itemize}
A plain citation looks like this \cite{Graham1995}, while multiple citations look like this
\cites{Graham1995}[see][p. 42]{Thomas2008}. We already used autocite, but we can also use the
similar smartcite \smartcite{Graham1995}. The benefit with smartcite is that you
can setup that e.g. all references should go into a footnote. You can continue
using smartcite when you are *in* a footnote and it will then detect that there
is no need for creating another footnote but behaving like autocite.Then, in our main.tex document, we’ll include each of
these files using the \input{filename}:
LATEX
\include{content/sections}
\include{content/lists}
\include{content/graphics}
\include{content/tables}
\include{content/cross-references}
\include{content/mathematics}
\include{content/fonts-and-spacing}
\include{content/reference-databases}Callout
Note that the \include{filename} command does not
require the .tex extension. LaTeX will assume that the file
is a .tex file if no extension is provided.
This is also true for someof the other commands we’ve seen, such as
\includegraphics{}. It is personal preference whether you
include the extension or not.
When we compile our document, we should see the same content as before, but now we can make changes in our content files, and the changes will be reflected in our main document.
Other Files
While we’re at it, let’s also create files for our packages, commands, and title page. We’ll also put these into their own directory called “preamble”:
preamble/packages.texpreamble/custom-commands.texpreamble/titlepage.tex
Our New main.tex
Our main.tex document should now look like this:
LATEX
% This command tells LaTeX what kind of document we are creating (article).
\documentclass{article}
\input{preamble/packages}
\input{preamble/custom-commands}
\addbibresource{sample-references.bib}
% Everything before the \begin{document} command is called the preamble.
\begin{document} % The document body starts here
\include{content/titlepage}
Hello World!
This is my first \kw{LaTeX} document.
\include{content/sections}
\include{content/lists}
\include{content/graphics}
\include{content/tables}
\include{content/cross-references}
\include{content/mathematics}
\include{content/fonts-and-spacing}
\include{content/reference-databases}
\printbibliography
\end{document}Callout
Note that we still need to put the content in the appropriate order.
For example, you can’t add \input{includes/packages} at the
end of the document, as it needs to be included before the document
starts.
Challenges
Challenge 1: Refactor Your Document with Multiple Files
Refactor the following LaTeX document to use multiple files.
LATEX
% This is the main document: main.tex
\documentclass{article}
\begin{document}
\begin{titlepage}
\centering
\huge
\textbf{My Custom LaTeX Title Page}
\vspace{1cm} % Space between title and subtitle
\normalsize
\textit{A Sample Document with Custom Formatting}
\vfill % Fill remaining space
\large
January 1, 2025
\end{titlepage}
\section{Tables}
\begin{tabular}{lll}
Fruit & Quantity & Price \\
Apple & 5 & 1.50 \\
Banana & 6 & 2.00 \\
Orange & 4 & 1.20 \\
\end{tabular}
\section{Graphics}
\begin{figure}[ht]
\centering
\includegraphics[height=2cm]{example-image.PNG}
\caption{This is a caption for our image.}
\end{figure}
\end{document}- Separate the content into different files for the sections by
tables.texandgraphics.tex. - Organize the file for the titlepage in a folder named “includes” and
name the file
titlepage.tex. - Organize the files for tables and graphics in a folder named “content”.
- Use the
\inputcommand to include the titlepage and the content in yourmain.texdocument.
LATEX
% This is the main document: main.tex
\documentclass{article}
\begin{document}
% Include title page
\input{includes/titlepage}
% Include content from different files in the "content" folder
\input{content/sections}
\input{content/lists}
\input{content/graphics}
\input{content/tables}
\input{content/cross-references}
\input{content/math}
\input{content/text-and-spacing}
\end{document}Challenge 2: Why did we do this?
In our content/tables.tex file, we have a bunch of
\input{} commands for the tables instead of writing the
tables directly in the file. Why did we do this? What is the benefit of
doing this?
Using an \input command inserts the table contents
directly into the document as though it was typed, which means that we
can reuse the same table in multiple documents without having to copy
paste it. For example, if we were making a presentation in LaTeX, we
could use the same table in our presentation. This means that if we make
a change to the table, it will be reflected in all of the documents in
which we use it.
(This reflects the programming principle of “Don’t Repeat Yourself” (DRY)!)
Challenge 3: Restructuring a larger document?
There isn’t a specific correct answer for this challenge, but one idea might be something that looks like this:
├── main.tex
├── preamble.tex
├── refereces.bib
├── content/
│ ├── introduction.tex
│ ├── model_architecture.tex
│ ├── model_results.tex
│ └── conclusion.tex
├── tables/
└── model_results.texKey Points
- LaTeX projects can contain many files that reference each other
- The
\input{filename}and\include{filename}commands allow you to include the contents of other files in your document - The
\frontmatter,\mainmatter,\backmatter, and\appendixcommands help structure your document