How can I label subfigures sequentially with positive integers across figures?

Question

I want to label subfigures, across many figures, with sequential positive integers.

For example, the first figure may have two subfigures with label tags {fig1:subfig1} and {fig1:subfig2} and the second figure may have three subfigures with label tags {fig2:subfig1}, {fig2:subfig2}, and {fig2:subfig3}.

Then, when referencing these labels,

{fig1:subfig1}
{fig1:subfig2}
{fig2:subfig1}
{fig2:subfig2}
{fig2:subfig3}

would display as

1
2
3
4
5.

How can I do this using the subfigure package?

I didn't know how to use the subfig package yet. In the meantime, there is a MWE using the subfigure package.

\documentclass[12pt]{article}
\usepackage{subfigure}
\begin{document}
\begin{figure}[ht]
 \subfigure[subfigure A]{This is a figure. \label{label1}}
 \subfigure[subfigure B]{This is a figure. \label{label2}}
\end{figure}
\begin{figure}[ht]
 \subfigure[subfigure A]{This is a figure. \label{label3}}
 \subfigure[subfigure B]{This is a figure. \label{label4}}
 \subfigure[subfigure C]{This is a figure. \label{label5}}
\end{figure}

Tesing referencing labels: \ref{label1} \ref{label2} \ref{label3} \ref{label4}

Desired result: 1 2 3 4 5
\end{document}

Answer 1

You need to disconnect the subfigure counter from the figure counter. This can be best done using the chngcntr package. It provides the \counterwithout{<counter>}{<parent counter>} macro for this and disconnects the <counter> from the original <parent counter>.

For the subfigure package you can use:

\usepackage{subfigure}% Actually replaced by `subfig`!
\usepackage{chngcntr}
\counterwithout{subfigure}{figure}

Update:

The above seems to work only for the sub-caption numbers but not for the references. You could add an own counter which is increased using \refstepcounter which makes it the target of the following \label.

The following code works for me. I hope it is what you want.

\documentclass[12pt]{article}
\usepackage{subfigure}

\newcounter{mysubfig}
\newcommand{\mysubfig}[2][]{%
    \subfigure[#1]{#2}%
    \refstepcounter{mysubfig}%
}

\usepackage{chngcntr}
\counterwithout{subfigure}{figure}
\renewcommand{\thesubfigure}{(\arabic{subfigure})}

\begin{document}
\begin{figure}[ht]
 \mysubfig[mysubfig A]{This is a figure.}\label{label1}
 \mysubfig[mysubfig B]{This is a figure.}\label{label2}
 \caption{Main caption}\label{main1}
\end{figure}
\begin{figure}[ht]
 \mysubfig[mysubfig A]{This is a figure.}\label{label3}
 \mysubfig[mysubfig B]{This is a figure.}\label{label4}
 \mysubfig[mysubfig C]{This is a figure.}\label{label5}
 \caption{Main caption}\label{main2}
\end{figure}

Main figure still work? \ref{main1} \ref{main2}

Tesing referencing labels: \ref{label1} \ref{label2} \ref{label3} \ref{label4} \ref{label5}

Desired result: 1 2 3 4 5
\end{document}

Result:

Answer 2

Not that the memoir class was specified, but in case it's useful to others, here's a MWE for multi-page figures with subfigures in memoir (I can't imagine another reason to not reset subfigure numbering when we get a new figure):

\documentclass[10pt,oneside]{memoir}

\newsubfloat{figure}

\begin{document}
\chapter{A Chapter}
The following figure (if it had real content) would be large
enough to require multiple pages. It is made of several subfigures,
labeled (a), (b), and (c). Though we have multiple figure environments,
the \verb|contsubbottom| command treats them as part of one logical
figure.
\begin{figure}
    \centering
    \subbottom[First Subfigure Caption]{
        \framebox[0.9\textwidth]{Here's the content of a subfigure.}
        \label{fig:ve_uw}
    }
    \\
    \subbottom[Second Subfigure Caption]{
        \framebox[0.9\textwidth]{Here's the content of a subfigure.}
        \label{fig:ve_iw}
    }
    \caption{First Figure Caption}
\end{figure}
%
\clearpage
%
\begin{figure}
    \centering
    \contsubbottom[Third Subfigure Caption]{
        \framebox[0.9\textwidth]{Here's the content of a subfigure.}
        \label{fig:ve_eiw}
    }
    \contcaption{Continued}
    \label{fig:ve}
\end{figure}
Since the previous figure has a subfigure on the top of this page,
we'll place this second figure anywhere *but* the top of the page.
\begin{figure}[hbp]
\centering
\framebox[0.9\textwidth]{Here's the content of another figure.}
\caption{Second Figure Caption}
\label{fig:second}
\end{figure}

\end{document}

Result:

Answer 3

The caption package provides \ContinuedFloat also for this purpose:

\documentclass[a4paper]{book}
\usepackage{subfig}
\usepackage{caption}
\captionsetup[subfloat]{listofformat=subsimple}
\renewcommand{\thesubfigure}{\arabic{subfigure}}
\usepackage[demo]{graphicx}
\begin{document}
text

\begin{figure}[htp]
\centering
\subfloat[first]{\includegraphics[width=3cm]{x}\label{f}}
\qquad
\subfloat[second]{\includegraphics[width=4cm]{x}\label{s}}
\caption{A figure}\label{full}
\end{figure}
\begin{figure}[htp]\ContinuedFloat
\centering
\subfloat[third]{\includegraphics[width=6cm]{x}\label{t}}
\caption{A figure (continued)}
\end{figure}

\subref{f}
\subref{s}
\subref{t}
\end{document}

Answer 4

This answer is based on Martin Scharrer's but used the subfig package (as he and others recommended).

I have (eventually) figured out how to use the subfig package and I really like the solution it provides for this problem. Because myCounter is not related to the figure or subfigure counters, everything else works (and thus looks) "normal".

\documentclass[12pt]{article}

\usepackage{subfig}
\newcounter{myCounter}
\newcommand{\mySubfloat}[2][]{\subfloat[#1]{#2}\refstepcounter{myCounter}}

\begin{document}
\begin{figure}[ht]
 \mySubfloat[mysubfig A]{This is a figure.}\label{label1}
 \mySubfloat[mysubfig B]{This is a figure.}\label{label2}
 \caption{Main caption}\label{main1}
\end{figure}
\begin{figure}[ht]
 \mySubfloat[mysubfig A]{This is a figure.}\label{label3}
 \mySubfloat[mysubfig B]{This is a figure.}\label{label4}
 \mySubfloat[mysubfig C]{This is a figure.}\label{label5}
 \caption{Main caption}\label{main2}
\end{figure}

Main figure still work? \ref{main1} \ref{main2}

Tesing referencing labels: \ref{label1} \ref{label2} \ref{label3} \ref{label4} \ref{label5}

Desired result: 1 2 3 4 5
\end{document}