How to make a combined "List of Figures and Tables"?

Question

I am aware of Combined List of Figures and Tables?, but the asker there requires one numbering scheme for figures and tables, which I don't want. Unfortunately, the answer seems to depend on that prerequisite.

My question is about an intended result/output like:

---

List of figures and tables

Figure 1: Map of trees in New Orleans .................................... 3

Figure 2: Number of leaves falling leaves per day ................... 5

Table 1:   Kinds of trees ........................................................ 12

Figure 3: Air quality reduction per 1000 fallen leaves ............ 20

---

For this to work, redefining figures to be tables (or the other way around) as suggested in the link above (i.e. something like \let\figure\table\let\endtable\endfigure) doesn't work because it of course causes all figures to be called "Table x" as well...

Answer 1

This works. The code is well commented so I don't think any more comments are needed.

\documentclass{article}

% To make the page shorter
\pagestyle{empty}
\textheight3in

% CODE STARTS HERE
% Based on `tocloft` package
\usepackage[titles]{tocloft}
\newlistof{figtab}{loft}{List of Figures and Tables}
\makeatletter
% Change the file extension of both lot and lof
\def\ext@figure{loft}
\def\ext@table{loft}
% Store the original `\thefigure` and `\thetable`
\let\tohe@thefigure\thefigure
\let\tohe@thetable\thetable
% Redefine them to contain a "dummy" `\tohe@list...`
\def\thefigure{\tohe@listfig\tohe@thefigure}
\def\thetable{\tohe@listtab\tohe@thetable}
% Make the two dummy commands truly dummy
\let\tohe@listfig\relax
\let\tohe@listtab\relax
% Store the original `\listoffigtab`
\let\tohe@listoffigtab\listoffigtab
% Redefine it in such a way that the dummy commands insert "Fig." or "Tab." respectively
\def\listoffigtab{%
  \begingroup
  \def\tohe@listfig{Fig.~}
  \def\tohe@listtab{Tab.~}
  \tohe@listoffigtab
  \endgroup  
}
% Change \listoffigtab spacing
\setlength{\cftfignumwidth}{5em}
\setlength{\cfttabnumwidth}{5em}
\setlength{\cftfigindent}{0pt}
\setlength{\cfttabindent}{0pt}
\makeatother
% CODE ENDS HERE

\begin{document}

\listoffigtab

% !b just to make the floats appear on the bottom of the first page
\begin{figure}[!b]
\caption{First}
\end{figure}

\begin{table}[!b]
\caption{Little Table}
\end{table}

\begin{figure}[!b]
\caption{Second}
\end{figure}

\end{document}

Answer 2

The relevant command is, as 'always' \addcontentsline.

figure and table captions are written to a file whose extension is stored in \ext@figure or \ext@table.

In \@caption (the internal processor macro actually) we find:

\long\def\@caption#1[#2]#3{%
  \par
  \addcontentsline{\csname ext@#1\endcsname}{#1}%
    {\protect\numberline{\csname the#1\endcsname}{\ignorespaces #2}}%
  \begingroup
    \@parboxrestore
    \if@minipage
      \@setminipage
    \fi
    \normalsize
    \@makecaption{\csname fnum@#1\endcsname}{\ignorespaces #3}\par
  \endgroup}

The first parameter of \@caption is the name of the float, i.e. figure or table (usually). This can be used and patched, grabbing the table captions and redirect them to the file with extension \ext@figure.

\documentclass{book}

\usepackage{caption}
\usepackage{xstring}
\usepackage{xpatch}

\makeatletter
\xpatchcmd{\@caption}{%
  \addcontentsline{\csname ext@#1\endcsname}{#1}%
  {\protect\numberline{\csname the#1\endcsname}{\ignorespaces #2}}%
}{%
  \IfStrEq{#1}{table}{% Filter `table` out
    \addcontentsline{\csname ext@figure\endcsname}{table}%
    {\protect\numberline{\csname the#1\endcsname}{\ignorespaces #2}}%
  }{%
    \addcontentsline{\csname ext@#1\endcsname}{#1}%
    {\protect\numberline{\csname the#1\endcsname}{\ignorespaces #2}}%
  }%
}{\typeout{Patch success}}{}
\makeatother

\renewcommand{\listfigurename}{List of Figures and Tables}

\begin{document}
\listoffigures
\begin{figure}
\caption{first figure}
\end{figure}

\begin{figure}
\caption{Another first figure}
\end{figure}


\begin{table}
\caption{first table}
\end{table}

\chapter{Another chapter}
\begin{table}
\caption{Yet another table}
\end{table}

\end{document}

A small update after yo' correctly noticed that it's unclear whether it's a table or figure in the LOFT:

\documentclass{book}

\usepackage{caption}
\usepackage{xstring}
\usepackage{tocloft}
\usepackage{xpatch}

\addtolength{\cftfignumwidth}{30pt}
\addtolength{\cfttabnumwidth}{30pt}
% Prepend the tab or fig number with a `\makebox` (for equal width) and put `Tab.` or `Fig.` in there. Change the names at will 
\renewcommand{\cfttabpresnum}{\makebox[30pt][l]{Tab.}}  
\renewcommand{\cftfigpresnum}{\makebox[30pt][l]{Fig.}}  


\makeatletter
\xpatchcmd{\@caption}{%
  \addcontentsline{\csname ext@#1\endcsname}{#1}%
  {\protect\numberline{\csname the#1\endcsname}{\ignorespaces #2}}%
}{%
  \IfStrEq{#1}{table}{%
    \addcontentsline{\csname ext@figure\endcsname}{table}%
    {\protect\numberline{\csname the#1\endcsname\hfill\hspace{1em}}{\ignorespaces #2}}%
  }{%
    \IfStrEq{#1}{figure}{%
      \addcontentsline{\csname ext@#1\endcsname}{#1}%
      {\protect\numberline{\csname the#1\endcsname\hfill\hspace{1em}}{\ignorespaces #2}}%
    }{%
     \addcontentsline{\csname ext@#1\endcsname}{#1}%
     {\protect\numberline{\csname the#1\endcsname}{ \ignorespaces #2}}%
    }
  }%
}{\typeout{Patch success}}{}
\makeatother

\renewcommand{\listfigurename}{List of Figures and Tables}

\begin{document}
\listoffigures
\begin{figure}
\caption{first figure}
\end{figure}

\begin{figure}
\caption{Another first figure}
\end{figure}


\begin{table}
\caption{first table}
\end{table}

\chapter{Another chapter}
\begin{table}
\caption{Yet another table}
\end{table}

\section{First section}
\subsection{First subsection}
\subsubsection{First subsubsection}
\begin{table}
\caption{Yet another another table}
\end{table}


\end{document}