Caption Woes: Understanding Inconsistent Latex Labeling Behaviors

Inconsistent Labeling in LaTeX Documents

Inconsistency in caption and reference labeling is a common issue that LaTeX users face. The underlying counters that track figures, tables, equations, and custom environments can sometimes increase in unexpected ways, leading to label numbers that seem out of order or reused across your document.

Understanding LaTeX's counter reset behaviors is key to diagnosing issues with inconsistent labeling. We'll explore the core concepts around counters in LaTeX and strategies you can use to wrangle labeling consistency for captions and cross-references across your projects.

Understanding Counter Reset Behavior

At a basic level, LaTeX's labeling relies on a system of underlying counters that increase sequentially as elements are placed in your document. For example, the figure counter tracks the number of \figure instances, automatically incrementing and making that value available through commands like \thefigure.

Issues arise when these counters get reset in unexpected ways. To understand this, we need to grasp LaTeX's hierarchy of counters, scope of resets, and how environments can override default reset behavior.

Global vs. Local Reset

Counters in LaTeX form a hierarchy, increasing across the entire document (global) or only within sections (local). For example, the equation counter resets every new section so your Eq. 1 always starts off a section.

More complex LaTeX packages like \chapter introduce additional scoping and stratification of counters. Now figures might reset per chapter while equations continue to reset per section. Understanding the breadth at which each counter resets is key to avoiding label inconsistencies.

Reset at Different Levels

Within the hierarchy, lower-level counters can be reset without affecting higher levels counters. For example, resetting the figure counter to restart figure numbering will leave the equation labels unaffected.

Resets can also cascade up the hierarchy, so resetting a high-level counter will trickle down and reset lower ones. If the section counter gets reset, you'll restart equation numbering as well.

Knowing which environments trigger counter resets at different levels is crucial for planning a labeling scheme that increments logically avoiding duplicated labels.

When Labels Don’t Reset as Expected

LaTeX's default reset behaviors work fine for basic documents, but start to break down with complex nesting of environments.

Custom environments can override defaults and neglect to reset counters that you might expect. For example, a custom proof environment that omits a figure counter reset can lead to unexpected duplicate figure labels if not addressed.

Understanding LaTeX's scoped counter reset system helps diagnose when environments cause unintended label increments leading to inconsistent references.

Tracking Down the Culprit Environment

When faced with jumping, duplicated, or unstable label numbers, systematically tracking down the environments causing issues can help resolve problems.

LaTeX provides debugger tools to inspect counter values, but we can also employ a binary search strategy to efficiently narrow in on problem code.

Using LaTeX Debugging Tools

Commands like \setcounter, \value, and \addtocounter let us manually control counters, while \showthe and \show provide visibility into current values.

Inserting debugging lines within suspicious environments can pinpoint unexpected resets or increments leading to counter value jumps.

This helps identify not just where the issue occurs but also which environments LaTeX believes are responsible based on its scoped reset rules.

Narrowing Down Problem Environments

To isolate rogue environments without debugging line clutter, temporarily remove halves of the LaTeX code to localize labeling issues.

Like a binary search algorithm, recursively narrow the code portions that could contain the problem environment. Checking document labels at each pass quickly converges on minimal code where issues manifest.

From here we can expand outward again, reintroducing environments until the counter instability returns allowing us to identify the environment causing unexpected resets.

Checking Package Documentation

Once a suspect environment emerges, consult its documentation for counter reset policies. Core LaTeX environments like \figure behave predictably but custom class files and packages may take liberties with resets.

Documentation may specify special reset rules explained, or show resets are omitted as a bug. Either way, awareness here helps reason about unnecessary label jumps based on environment assumptions.

For orphaned packages with sparse documentation, the environment source code itself also can provide hints to reset triggers.

Strategies for Consistent Labeling

After pinpointing environments that upset counter consistency, several approaches can help impose stability on label numbering across a document.

Targeted counter resets, environment modifications, and label namespacing provide control mechanisms to align labels with intended presentation order.

Resetting Counters Manually

Insert \setcounter resets before culprit environments to safely restart numbering and prevent duplicate labels

Strategic resets aligned with sectioning hierarchy steers environments onto an expected track preventing incidental increases from prior context.

Manual resets do add line noise, but require no environment internals modification providing a simple counter override option

Changing Environment Definitions

For complex documents with many custom environments, globally updating an environment definition to reset labels provides a central fix.

Alter the environment's \BeforeBegin or \AfterEnd handler to add needed resets supporting consistent numbering

This avoids reset clutter at individual environment sites, imposing stability for all instances in one place.

Using Label Prefixes

Rather than fight an environment's reset rules, add unique prefixes to its labels and references to deconflict other numbering.

For example figures may be labeled fig:1, fig:2 while custom theorem environments start thm:1, thm:2.

Keeping independent label sets avoids collision even if counter values internally overlap due to scoping difference

Example Code Snippets

To demonstrate counter reset principles in action, the following examples manipulate figure environment numbering to avoid duplications.

The same approaches apply more generally to impose consistency across other labeling use cases when standard LaTeX reset behaviors fall short.

Basic Counter Reset

Reset the figure counter before problems emerge to sidestep duplicate labels

  \begin{document}
    
    \section{First section}
      \begin{figure}
         \caption{First figure}
      \end{figure}

    \section{Second section}
      
      % Reset figure counter
      \setcounter{figure}{0} 
    
      \begin{figure}
        \caption{Second figure (no longer Figure 2)}
      \end{figure}

  \end{document}  

Custom Environment with Reset

Modify a custom proof environment definition to always reset figures.

  \newenvironment{proof}[1]{
    % Reset figure counter 
    \setcounter{figure}{0}
    
    \begin{trivlist} ...
  }{
    \end{trivlist}
  }

  \begin{document}

    \begin{figure}
       \caption{A figure}
    \end{figure}

    \begin{proof}
      \begin{figure}
         \caption{Now Figure 2 even inside proof}
      \end{figure}
   \end{proof}

  \end{document}

Adding Label Prefixes

Disambiguate labels between standard figures and custom diagrams

  \newenvironment{diagram} {...}{...}

  \begin{document}

    \begin{figure}
      \caption{Figure \thefigure: Important result}
       \label{fig:\thefigure} 
    \end{figure}

    \begin{diagram}
      \caption{Diagram \thediagram: Process overview}
      \label{dia:\thediagram}
    \end{diagram}

    Figure \ref{fig:1} demonstrates...
    while Diagram \ref{dia:1} shows...

  \end{document}