Random number without repetition in an \includegraphics

Question

I have 58 images in PDF format. At the moment, each of them is in a separate PDF, such as 1.pdf, 2.pdf etc. I would like to include those 58 images in a random order without repetition.

I found the 'random order without repetitition' part: Generating random numbers without repetitions

So very candidly, this is what I did (minimal code):

\documentclass[a4paper,12pt]{article} 
\usepackage{tikz}

\begin{document}

%here is the bit from the link above to randomly draw a number from a list of integers without repetition
\def\declarenumlist#1#2#3{%
    \expandafter\edef\csname pgfmath@randomlist@#1\endcsname{#3}%
    \count@\@ne
    \loop
    \expandafter\edef
    \csname pgfmath@randomlist@#1@\the\count@\endcsname
    {\the\count@}
    \ifnum\count@<#3\relax
    \advance\count@\@ne
    \repeat}

%I want 58 numbers because I have 58 images
\declarenumlist{total}{1}{58}

%I try to include my pdf
\includegraphics{\pgfmathrandomitem\z{total}\z.pdf}

\end{document}

Of course, this does not work, the reason being I suppose '\includegraphics should be a file name (after macro expansion), not the set of instructions to compute it', as explained in How to include random images?. I tried to follow the route suggested in this question, by doing a

\newcommand{\myrandomnumber}{\pgfmathrandomitem\z{total}\z}
\includegraphics{\myrandomnumber.pdf}

But this does not work either.

Note that, if needed, I can keep my 58 images in the same pdf (they are pdflatex generated) and use a \includepdf[pages={\pgfmathrandomitem\z{total}\z}]{images.pdf}, but this does not work either, I think for the same reasons.

Does anyone know what's going on (I would like to understand) and then how to fix my problem? Any help would be very much appreciated.

Answer 1

You should put \makeatletter and \makeatother around the definition of \declarenumlist and move \pgfmathrandomitem\z{total} outside the argument to \includegraphics like in

\pgfmathrandomitem\z{total}\includegraphics{\z.pdf}

However I would recommend a different definition of \declarenumlist that doesn't depend on the actual way a list for random choice is internally built by TikZ/PGF.

In the code below the list of numbers from the lowest bound to the highest bound is generated and fed as argument to \pgfmathdeclarerandomlist. The loop is very similar, but, as said, the macro will continue to work even if TikZ/PGF changes the internals of these lists.

Next I define an interface for \includegraphics: the \randomincludegraphics command accepts options to pass to \includegraphics and its mandatory argument is the list name.

Since I don't have the files to play with, I just hid the real macro to call and used a mock text for showing the effect.

\documentclass[a4paper,12pt]{article} 
\usepackage{tikz}
\begin{document}
\makeatletter
\def\declarenumlist#1#2#3{%
  \begingroup
  \count@=#2\relax
  \def\x{}%
  \loop
  \edef\x{\x{\the\count@}}%
  \ifnum\count@<#3\relax
    \advance\count@@ne
  \repeat
  \edef\x{\endgroup
    \noexpand\pgfmathdeclarerandomlist{#1}{\x}%
  }\x
}
\makeatother
\newcommand{\randomincludegraphics}[2][]{%
  \begingroup
  \pgfmathrandomitem\z{#2}%
% Uncomment the following line for the production version

%  \includegraphics[#1]{\z}%
% and remove the following line
  I want to include \texttt{\z.pdf} with options ``\texttt{#1}''%
  \endgroup
}
%I want 58 numbers because I have 58 images
\declarenumlist{total}{1}{58}
\randomincludegraphics{total}
\randomincludegraphics{total}
\randomincludegraphics[height=3cm,width=1cm]{total}
\end{document}

---

Here's a version that avoids repetitions; if it's called more times than the available items, random repetitions are used (with a warning). You have to redeclare the list, if you want to use it another time.

\documentclass[a4paper,12pt]{article} 
\usepackage{tikz}
\begin{document}
\makeatletter
\def\declarenumlist#1#2#3{%
  @ifundefined{c@#1@listcount}{\newcounter{#1@listcount}}{}%
  \setcounter{#1@listcount}{1}%
  \begingroup
  \count@=#2\relax
  \def\x{}%
  \loop
  \edef\x{\x{\the\count@}}%
  \global\expandafter\let\csname#1@\number\count@ @used\endcsname\relax
  \ifnum\count@<#3\relax
    \advance\count@@ne
    \stepcounter{#1@listcount}%
  \repeat
  \edef\x{\endgroup
    \noexpand\pgfmathdeclarerandomlist{#1}{\x}%
  }\x
  \expandafter\mathchardef\csname #1@number\endcsname\value{#1@listcount}%
  \setcounter{#1@listcount}{0}%
}
\newcommand{\pgfmathuniquerandomitem}[2]{%
  \pgfmathrandomitem#1{#2}%
  \ifnum\value{#2@listcount}=@nameuse{#2@number}%
    @latex@warning{List #2 exhausted}%
  \else
    @ifundefined{#2@#1@used}%
      {\stepcounter{#2@listcount}\global@namedef{#2@#1@used}{used}}%
      {\pgfmathuniquerandomitem#1{#2}}%
  \fi
}
\makeatother
\newcommand{\randomincludegraphics}[2][]{%
  \begingroup
  \pgfmathuniquerandomitem\z{#2}%
% Uncomment the following line for the production version

%  \includegraphics[#1]{\z}
% and remove the following line
  I want to include \texttt{\z.pdf} with options ``\texttt{#1}''
  \endgroup
}
%I want 58 numbers because I have 58 images
\declarenumlist{total}{1}{58}
\randomincludegraphics{total}
\randomincludegraphics{total}
\randomincludegraphics[height=3cm,width=1cm]{total}
\foreach\i in {1,...,58} { \randomincludegraphics{total}\endgraf }
\declarenumlist{total}{1}{58} % redeclare the list
\foreach\i in {1,...,58} { \randomincludegraphics{total}\endgraf }
\end{document}

Update 2022

There are much better ways now to do the same task.

\documentclass[a4paper]{article}
\ExplSyntaxOn
% just for using all items
\NewDocumentCommand{\myforeach}{m +m}
 {
  \int_step_inline:nn { #1 } { #2 }
 }
%%%%
\NewDocumentCommand{\declarerandomlist}{mO{1}m}
 {% #1 = list name
  % #2 = start point (default 1)
  % #3 = end point
  \egreg_randomlist_declare:nnn { #1 } { #2 } { #3 }
 }
\NewDocumentCommand{\usefromrandomlist}{mm}
 {% #1 = list name
  % #2 = template
  \egreg_randomlist_use:nn { #1 } { #2 }
 }
\cs_new_protected:Nn \egreg_randomlist_declare:nnn
 {
  \seq_clear_new:c { l_egreg_randomlist_#1_seq }
  \bool_do_until:nn { \int_compare_p:n { \seq_count:c { l_egreg_randomlist_#1_seq } = #3-#2+1 } }
   {
    \seq_put_left:cx { l_egreg_randomlist_#1_seq } { \int_rand:nn { #2 } { #3 } }
    \seq_remove_duplicates:c { l_egreg_randomlist_#1_seq }
   }
 }
\cs_new_protected:Nn \egreg_randomlist_use:nn
 {
  \cs_set:Nn __egreg_randomlist:n { #2 }
  \seq_if_empty:cTF { l_egreg_randomlist_#1_seq }
   {
    \msg_warning:nnn { randomlist } { exhausted } { #1 }
   }
   {
    \seq_pop_left:cN { l_egreg_randomlist_#1_seq } \l__egreg_randomlist_item_tl
    __egreg_randomlist:V \l__egreg_randomlist_item_tl
   }
 }
\tl_new:N \l__egreg_randomlist_item_tl
\cs_new_protected:Nn __egreg_randomlist:n { } % initialize
\cs_generate_variant:Nn __egreg_randomlist:n { V }
\msg_new:nnn { randomlist } { exhausted } {List ~ #1 ~ exhausted}
\ExplSyntaxOff
\newcommand{\randomincludegraphics}[2][]{%
% Uncomment the following line for the production version

%  \usefromrandomlist{#2}{\includegraphics[#1]{##1}
% and remove the following line
  \usefromrandomlist{#2}{I want to include \texttt{##1.pdf} with options ``\texttt{#1}''}
}
\begin{document}
\declarerandomlist{total}{5}
\randomincludegraphics{total}
\randomincludegraphics{total}
\randomincludegraphics[height=3cm,width=1cm]{total}
\myforeach{5}{\randomincludegraphics{total}\par}
\end{document}

The main difference, apart from the names, is that

\usefromrandomlist

takes as arguments the list name and a template where #1 stands for the current item in the random list, so one can do

\usefromrandomlist{total}{\includegraphics{#1.pdf}}

or abstract the command (like in the code above), remembering that #1 has to become ##1.