LaTeX loops

Today I was writing a report which included 20 figures, with the names demandplot1.pdf, demandplot2.pdf, …, demandplot20.pdf, and all with similar captions. Clearly a loop was required. After all, LaTeX is a programming language, so we should be able to take advantage of its capabilities.

I found the forloop package which handled the problem perfectly. My first attempt looked like this:

\newcommand{\demandplot}[1]{\begin{figure}\centering
\includegraphics[width=\textwidth]{./figs/demandplot#1.pdf}
\caption{Hourly demand (GW) for zone #1.}
\end{figure}}

\newcounter{loop}
\forloop{loop}{1}{\value{loop}<21}{\demandplot{\arabic{loop}}}

The magic happens in the last line providing a loop from 1 to 20, generating the commands \demandplot{1}, \demandplot{2}, …, \demandplot{20}.

However, that didn’t work. After examining the log file, it seems that LaTeX can’t handle 20 figures in a row as it has to store them up while it looks for where to place them. So the following modified code was used:

\newcommand{\demandplot}[1]{\begin{figure}\centering
\includegraphics[width=\textwidth]{./figs/demandplot#1.pdf}
\caption{Hourly demand (GW) for zone #1.}
\end{figure}}

\newcounter{loop}
\forloop{loop}{1}{\value{loop}<11}{\demandplot{\arabic{loop}}}
\clearpage
\forloop{loop}{11}{\value{loop}<21}{\demandplot{\arabic{loop}}}

This loops from 1 to 10, then the \clearpage command processes all floats before proceeding with the loop from 11 to 20.

Any time you need some repetitive code in LaTeX, the forloop package should make your life easier (and make silly mistakes less likely).