1

I found a great code to get n random questions from bankA.tex

Generate exam from a question bank?

But I only need to get an nth question in bankA? for example: \getquestionsfrombank{bankA.tex}{6}, then we only get the 6th question (Question 6) in the bankA.tex. Can you help me?

\documentclass{article}
\usepackage{multicol}% Just for this example
\usepackage{filecontents}
\begin{filecontents*}{bankA.tex}
\begin{questionblock}
Question 1
\end{questionblock}
\begin{questionblock}
Question 2
\end{questionblock}
\begin{questionblock}
Question 3
\end{questionblock}
\begin{questionblock}
Question 4
\end{questionblock}
\begin{questionblock}
Question 5
\end{questionblock}
\begin{questionblock}
Question 6
\end{questionblock}
\begin{questionblock}
Question 7
\end{questionblock}
\begin{questionblock}
Question 8
\end{questionblock}
\begin{questionblock}
Question 9
\end{questionblock}
\begin{questionblock}
Question 10
\end{questionblock}
\end{filecontents*}

\usepackage{catchfile,environ,tikz}

\makeatletter% Taken from https://tex.stackexchange.com/q/109619/5764
\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}
\def\prunelist#1{%
  \expandafter\xdef\csname pgfmath@randomlist@#1\endcsname
          {\the\numexpr\csname pgfmath@randomlist@#1\endcsname-1\relax}
  \count@\pgfmath@randomtemp 
  \loop
    \expandafter\global\expandafter\let
    \csname pgfmath@randomlist@#1@\the\count@\expandafter\endcsname
    \csname pgfmath@randomlist@#1@\the\numexpr\count@+1\relax\endcsname
    \ifnum\count@<\csname pgfmath@randomlist@#1\endcsname\relax
      \advance\count@\@ne
  \repeat}
\makeatother

% Define how each questionblock should be handled
\newcounter{questionblock}
\newcounter{totalquestions}
\NewEnviron{questionblock}{}%

\newcommand{\randomquestionsfrombank}[2]{%
  \CatchFileDef{\bank}{#1}{}% Read the entire bank of questions into \bank
  \setcounter{totalquestions}{0}% Reset total questions counters  ***
  \RenewEnviron{questionblock}{\stepcounter{totalquestions}}% Count every question  ***
  \bank% Process file  ***
  \declarenumlist{uniquequestionlist}{1}{\thetotalquestions}% list from 1 to totalquestions inclusive.
  \setcounter{totalquestions}{#2}% Start the count-down
  \RenewEnviron{questionblock}{%
    \stepcounter{questionblock}% Next question
    \ifnum\value{questionblock}=\randomquestion 
      \par% Start new paragraph
      \BODY% Print question
    \fi
  }%
  \foreach \uNiQueQ in {1,...,#2} {% Extract #2 random questions
    \setcounter{questionblock}{0}% Start fresh with question block counter
    \pgfmathrandomitem\randomquestion{uniquequestionlist}% Grab random question from list
    \xdef\randomquestion{\randomquestion}% Make random question available globally
    \prunelist{uniquequestionlist}% Remove picked item from list
    \bank% Process file
  }}

\begin{document}

\begin{multicols}{3}
  \foreach \x in {1,...,6} {
    \bigskip
    \randomquestionsfrombank{bankA.tex}{6}
  }
\end{multicols}

\end{document}
2

1 Answer 1

2

Updated

Usage:

% parse all questions from "bankA.tex"
\storequestionsfrombank{bankA.tex}

\begin{multicols}{3}
  % print questions 1, 3, 5, and 7 in order
  \foreach \x in {1,3,5,7} {
    \pickquestionfrombank{\x}
  }
\end{multicols}

Definition:

% read file #1, store quesion <num> in \question@body@<num>
\newcommand{\storequestionsfrombank}[1]{%
  \CatchFileDef{\bank}{#1}{}% Read the entire bank of questions into \bank
  \RenewEnviron{questionblock}{%
    \stepcounter{totalquestions}%
    \expandafter\global\expandafter\let
    \csname question@body@\the\value{totalquestions}\endcsname\BODY
  }%
  \setcounter{totalquestions}{0}%
  \bank}

% print question #1 in constant time
\newcommand\pickquestionfrombank[1]{%
  \par
  \@nameuse{question@body@#1}%
}

Original answer

With this new command

% print question #2 from bank #1 in linear time
\newcommand{\pickquestionsfrombank}[2]{%
  \CatchFileDef{\bank}{#1}{}% Read the entire bank of questions into \bank
  \setcounter{totalquestions}{0}% Reset total questions counters  ***
  \RenewEnviron{questionblock}{%
    \stepcounter{totalquestions}% Next question
    \ifnum\value{totalquestions}=#2 
      \par% Start new paragraph
      \BODY% Print question
    \fi
  }%
  \setcounter{totalquestions}{0}%
  \bank}

input

\pickquestionsfrombank{bankA.tex}{<number>}

will print content of question <number>.


Full example:

\begin{filecontents}[force]{bankA.tex}
\begin{questionblock}
Question 1
\end{questionblock}
\begin{questionblock}
Question 2
\end{questionblock}
\begin{questionblock}
Question 3
\end{questionblock}
\begin{questionblock}
Question 4
\end{questionblock}
\begin{questionblock}
Question 5
\end{questionblock}
\begin{questionblock}
Question 6
\end{questionblock}
\begin{questionblock}
Question 7
\end{questionblock}
\begin{questionblock}
Question 8
\end{questionblock}
\begin{questionblock}
Question 9
\end{questionblock}
\begin{questionblock}
Question 10
\end{questionblock}
\end{filecontents}

\documentclass{article}
\usepackage{multicol}% Just for this example
\usepackage{catchfile,environ,tikz}

\makeatletter% Taken from https://tex.stackexchange.com/q/109619/5764
\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}
\def\prunelist#1{%
  \expandafter\xdef\csname pgfmath@randomlist@#1\endcsname
          {\the\numexpr\csname pgfmath@randomlist@#1\endcsname-1\relax}
  \count@\pgfmath@randomtemp 
  \loop
    \expandafter\global\expandafter\let
    \csname pgfmath@randomlist@#1@\the\count@\expandafter\endcsname
    \csname pgfmath@randomlist@#1@\the\numexpr\count@+1\relax\endcsname
    \ifnum\count@<\csname pgfmath@randomlist@#1\endcsname\relax
      \advance\count@\@ne
  \repeat}
\makeatother

% Define how each questionblock should be handled
\newcounter{questionblock}
\newcounter{totalquestions}
\NewEnviron{questionblock}{}%

\newcommand{\randomquestionsfrombank}[2]{%
  \CatchFileDef{\bank}{#1}{}% Read the entire bank of questions into \bank
  \setcounter{totalquestions}{0}% Reset total questions counters  ***
  \RenewEnviron{questionblock}{\stepcounter{totalquestions}}% Count every question  ***
  \bank% Process file  ***
  \declarenumlist{uniquequestionlist}{1}{\thetotalquestions}% list from 1 to totalquestions inclusive.
  \setcounter{totalquestions}{#2}% Start the count-down
  \RenewEnviron{questionblock}{%
    \stepcounter{questionblock}% Next question
    \ifnum\value{questionblock}=\randomquestion 
      \par% Start new paragraph
      \BODY% Print question
    \fi
  }%
  \foreach \uNiQueQ in {1,...,#2} {% Extract #2 random questions
    \setcounter{questionblock}{0}% Start fresh with question block counter
    \pgfmathrandomitem\randomquestion{uniquequestionlist}% Grab random question from list
    \xdef\randomquestion{\randomquestion}% Make random question available globally
    \prunelist{uniquequestionlist}% Remove picked item from list
    \bank% Process file
  }}

\newcommand{\pickquestionsfrombank}[2]{%
  \CatchFileDef{\bank}{#1}{}% Read the entire bank of questions into \bank
  \RenewEnviron{questionblock}{%
    \stepcounter{totalquestions}% Next question
    \ifnum\value{totalquestions}=#2 
      \par% Start new paragraph
      \BODY% Print question
    \fi
  }%
  \setcounter{totalquestions}{0}%
  \bank}

\begin{document}

\begin{multicols}{3}
  \foreach \x in {1,3,5,7} {
    \pickquestionsfrombank{bankA.tex}{\x}
  }
  % this prints questions 1, 3, 5, and 7 in order
\end{multicols}

\end{document}

Note that since latex2e 2019-10-01, package filecontents is deprecated and its utility is merged into latex2e. So I replace environment filecontents* by \begin{filecontents}[force]{bankA.tex}.

1
  • I have updated my answer to add a constant-time implementation. Mar 23, 2020 at 13:49

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