Reformat a string and remove leading zeros from substrings

Question

I have strings such as

2011-10-29--2-03

but I want to display them as

2011-10-29, p. 2, fig. 3

I tried

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{xstring}
\begin{document}
\def\ConvertID#1{%
\StrMid{#1}{1}{10}, 
p.~\StrMid{#1}{13}{13}, 
fig.~\StrMid{#1}{15}{16}
}
See \ConvertID{2011-10-29--2-03}.
\end{document}

and then tried various methods (from ideas at Remove leading zeroes from an integer) to handle the last 2 characters, e.g.

\num[minimum-integer-digits=1]{\StrMid{#1}{15}{16}}

from siunitx, but it did not work.

How can this be done?

Answer 1

\documentclass{article}
\def\foo#1{\xfoo#1\relax}
\def\xfoo#1--#2-#3\relax{#1, p.\ \number#2, fig.\ \number#3\relax}
\begin{document}
\foo{2011-10-29--2-03}
\end{document}

Answer 2

The following code is similar to David's, but it doesn't assume that page or figure numbers only consist of digits. For this to work we need to eat up leading zeros.

\documentclass{article}
\ExplSyntaxOn
\NewExpandableDocumentCommand{\ConvertID}{m}
 {
  \mflxvii_convert:n { #1 }
 }
\cs_new:Nn \mflxvii_convert:n
 {
  __mflxvii_convert:w #1 \q_stop
 }
\cs_new:Npn __mflxvii_convert:w #1--#2-#3 \q_stop
 {% #1 is a date in ISO format, #2 is a page number, #3 is a figure number
  #1,~
  p.\ __mflxvii_convert_eat:N #2 \q_nil ,~
  f.\ __mflxvii_convert_eat:N #3 \q_nil
 }
\cs_new:Nn __mflxvii_convert_eat:N
 {
  \quark_if_nil:NF #1
   {
    \str_if_eq:nnTF { #1 } { 0 }
     {% a zero, restart
      __mflxvii_convert_eat:N
     }
     {% not a zero, finish up
      #1 __mflxvii_convert_deliver:w
     }
   }
 }
\cs_new:Npn __mflxvii_convert_deliver:w #1 \q_nil { #1 }
\ExplSyntaxOff
\begin{document}
\ConvertID{2011-10-29--22-03}
\ConvertID{2011-10-29--022-3}
\ConvertID{2011-10-29--22-a2}
\edef\test{\ConvertID{2011-10-29--22-a2}}
\texttt{\meaning\test}
\end{document}

If expandability is not of a concern, here's a variant of matexmatics' answer

\documentclass{article}
\ExplSyntaxOn
\NewDocumentCommand{\ConvertID}{m}
 {
  \mflxvii_convert:n { #1 }
 }
\seq_new:N \l__mflxvii_convert_seq
\tl_new:N \l__mflxvii_convert_tl
\cs_new_protected:Nn \mflxvii_convert:n
 {
  \seq_set_split:Nnn \l__mflxvii_convert_seq { - } { #1 }
  \seq_item:Nn \l__mflxvii_convert_seq { 1 } -
  \seq_item:Nn \l__mflxvii_convert_seq { 2 } -
  \seq_item:Nn \l__mflxvii_convert_seq { 3 } ,~
  p.\nobreakspace __mflxvii_convert_eat:e { \seq_item:Nn \l__mflxvii_convert_seq { 5 } },~
  f.\nobreakspace __mflxvii_convert_eat:e { \seq_item:Nn \l__mflxvii_convert_seq { 6 } }
 }
\cs_new_protected:Nn __mflxvii_convert_eat:n
 {
  \tl_set:Nn \l__mflxvii_convert_tl { #1 }
  \regex_replace_once:nnN { \A 0* } { } \l__mflxvii_convert_tl
  \tl_use:N \l__mflxvii_convert_tl
 }
\cs_generate_variant:Nn __mflxvii_convert_eat:n { e }
\ExplSyntaxOff
\begin{document}
\ConvertID{2011-10-29--22-03}
\ConvertID{2011-10-29--022-3}
\ConvertID{2011-10-29--22-a2}
\end{document}

Answer 3

The answer below uses \seq_set_split:Nnn to split the argument of \FormatDatePageFig. It applies \int_to_arabic:n to the last item of this sequence.

\documentclass[border=6pt]{standalone}
\ExplSyntaxOn
\seq_new:N \l__mf_format_seq
\NewDocumentCommand { \FormatDatePageFig } { m }
  {
    \seq_set_split:Nnn \l__mf_format_seq { - } {#1}
    \seq_item:Nn \l__mf_format_seq { 1 } -
    \seq_item:Nn \l__mf_format_seq { 2 } -
    \seq_item:Nn \l__mf_format_seq { 3 } , ~ p. ~
    \seq_item:Nn \l__mf_format_seq { 5 } , ~ fig. ~
    \int_to_arabic:n { \seq_item:Nn \l__mf_format_seq { 6 } }
  }
\ExplSyntaxOff
\begin{document}
\FormatDatePageFig{2011-10-29--2-03}
\end{document}

Answer 4

\documentclass{article}
\usepackage{listofitems}
\setsepchar{-}
\newcommand\convertID[1]{%
  \readlist*\theID{#1}%
  \theID[1]-\theID[2]-\theID[3], p.\ \theID[5], fig.\ \number\theID[6]%
}
\begin{document}
\convertID{2011-10-29--2-3}
\end{document}

Answer 5

The following solution employs LuaLaTeX and works with any utf8-encoded string, not just ASCII-encoded strings. It doesn't assume that the page or figure numbers consist of exactly 1 or 2 digits, respectively.

\documentclass{article}
\usepackage{luacode} % for 'luacode' environment
\begin{luacode}

  function Convert ( s )
    s1=unicode.utf8.sub( s , 1 , 10 )
s2=unicode.utf8.match ( unicode.utf8.sub(s,13) , "^.-%-" )
s2=tonumber(unicode.utf8.sub(s2,1,-2))

s3=unicode.utf8.match( s , "-%d*$" )
s3=tonumber(unicode.utf8.sub ( s3, 2 ))

return ( s1 .. ", p.\\ " .. s2 .. ", fig.\\ " .. s3)

end

\end{luacode}
\newcommand\Convert[1]{\directlua{tex.sprint(Convert("#1"))}}

\begin{document}
\Convert{2011-10-29--2-03}

\Convert{2023-12-30--0123-01234}
\end{document}