[Tex/LaTex] Create a LibreOffice spreadsheet from luatex

automationluatexopen-office

After reading this amazing answer, I'm wondering if it possible to do the same thing but the other way round, that is create a LibreOffice spreadsheet from luatex, exporting data from the tex file to the spreadsheet.

The example I have in mind is: say I'm typesetting the solution of an exam with a documentclass that defines a macro \answer to be used in the following context.

\documentclass{myclass}

\begin{document}

\section{Test 1}

\begin{enumerate}
\item The \answer{definition of entropy} states that \answer{$S = k_B
    \ln \Omega$}. 
\end{enumerate}

\end{document}

I grade my students with a LibreOffice spreadsheet. So I'd like luatex to create (or modify) a spreasheet so I can have automatically something like in the screenshot below.

screenshot of spreadsheet

I understand that a lua interface to LibreOffice does not exist. So I see three ways here:

  1. Creating a zip file from scratch meeting the .ods standard.
  2. Using some magic to interface LibreOffice API with luatex (with LuaJava?).
  3. Using some perl or other kind of magic to do the job.

As @canaaerus suggested in comments, I could export things from tex with a csv file but I'd like to have a real .ods out of the box so that I could have style information (like bold face, centered text, etc.) and formulas.

Best Answer

Edit 14-08-2012 New version of odsfile incorporates ideas from this answer. It is now possible to use following code:

\documentclass{article}
\usepackage{lmodern,odsfile,booktabs}
\begin{document}
\loadodsfile{template.ods}

\begin{AddRow}
\AddString{Hello world}{}
\AddNumber{46}{3}
\end{AddRow}

\includespread[template=booktabs,columns=head]
\savespreadsheet
\end{document}

Package is now included in TeX Live and xml library is distributed separately http://ctan.org/pkg/luaxml, so now it can be used by other packages.

This is my solution using lualatex and development version of odsfile. First of all, I created serialization function from LuaXML tables to xml.

Code

xml = require("xml-mod")
local t = {html={head = {title = "Hello world"}}} -- Table in format as created with LuaXML parser
print(xml.serialize(t))

outputs

<?xml version="1.0" encoding="UTF-8"?>
<html>
  <head>
    <title>Hello world</title>
  </head>
</html>

Then there is small library for adding contents to ods file, exams.lua

module(...,package.seeall)
require("odsfile")
xml = require("xml-mod")


function updateZip(zipfile, updatefile)
  local command  =  string.format("zip %s %s",zipfile, updatefile)
  print ("Updating an ods file.\n" ..command .."\n Return code: ", os.execute(command))  
end

-- Object for adding new rows 

function newRow()
  local p = {
    pos = 0,
    cells = {},
    -- Generic function for inserting cell
    addCell = function(self,val, attr,pos)
      if pos then
        table.insert(self.cells,pos,{["text:p"] = val, ["_attr"] = attr})
        self.pos = pos
      else
        self.pos = self.pos + 1
        table.insert(self.cells,self.pos,{["text:p"] = val, ["_attr"] = attr})
      end
    end, 
    addString = function(self,s,attr,pos)
      local attr = attr or {}
      attr["office:value-type"] = "string"
      self:addCell(s,attr,pos)
    end,
    addFloat = function(self,i,attr,pos)
      local attr = attr or {}
      local s = tonumber(i) or 0
      s = tostring(s)
      attr["office:value-type"] = "float"
      attr["office:value"] = s
      self:addCell(s,attr,pos)
    end, 
    findLastRow = function(self,sheet)
      for i= #sheet["table:table-row"],1,-1 do
        if sheet["table:table-row"][i]["_attr"]["table:number-rows-repeated"] then
          return i
        end
      end
    end,
    insert = function(self, sheet, pos)
      local t = {}
      local pos = pos or self:findLastRow(sheet)
      for i=1, #sheet["table:table-column"] do
        table.insert(t,self.cells[i] or {})  
      end
      t = {["table:table-cell"]=t}
      table.insert(sheet["table:table-row"],pos,t)
    end
  }
  return p
end

It has one function and one object. updateZip(zipfile, updatefile) tries to run zip utility, which have to be installed in your system. Unfortunately, I have some problems with access rights on my computer, so it doesn't work here. Instead, I just run this command from commandline using generated xml and it works just fine.

newRow() returns object with some methods:

  • addCell(val,attr,pos)
  • addString(val,attr,pos)
  • addNumber(val,attr,pos) these methods add columns into row. addCell is generic one and should not be used. attr is array with attributes, you can leave it empty. pos means position of the column in the row, it can also be nil
  • insert(sheet, pos) this function insert row to the sheet, you can specify row position with pos

Now some simple LaTeX package, exams.sty

\ProvidesPackage{exams}
\RequirePackage{luacode}
\begin{luacode}
exams = require("exams")
require("odsfile")
xml = require("xml-mod")
--exams.test()
row      = {}
sheet    = {}
ods      = {}
filename = ""
\end{luacode}

\newcommand\examspreadsheet[2]{%
 \luaexec{%
  sh = "\luatexluaescapestring{#2}"
  if sh == "" then sh = nil end
  filename = "\luatexluaescapestring{#1}"
  local f   = odsfile.load(filename)
  ods = f:loadContent()
  sheet = odsfile.getTable(ods,sh)
 }
}

\newcommand\savespreadsheet{%
\luaexec{exams.updateZip(filename,"content.xml")}
}
\newcommand\answer[1]{%
\begingroup%
\AddRow%
\AddNumber{\theenumi}{}%
\AddString{#1}{}%
\endAddRow%
\endgroup%
#1%
}
\newenvironment{exam}[1]{%
\section{#1}
\AddRow
\AddString{#1}{}
\endAddRow
\enumerate%
}{\endenumerate%
 \luaexec{%
   f = io.open("content.xml","w")
   f:write(xml.serialize(ods.root))
 }
}

\newenvironment{AddRow}[1][]{%
\def\AddString##1##2{% 
\luaexec{%
local pos = "\luatexluaescapestring{##2}"%
if pos == "" then pos = nil end; row:addString("\luatexluaescapestring{\unexpanded{##1}}",nil,pos)%
}%
}%
\def\AddNumber##1##2{%
\luaexec{%
local pos = "\luatexluaescapestring{##2}"%
if pos == "" then pos = nil end; row:addFloat("\luatexluaescapestring{##1}",nil,pos)%
}%
}%
\luaexec{%
pos = "\luatexluaescapestring{#1}"%
if pos == "" then pos = nil end; row = exams.newRow()%
}
}{%
\luaexec{%
row:insert(sheet,pos)%
}
}

This package defines three user commands and one environment:

  • \examspreadsheet{odsfile}{sheet} loads sheet from file. you can left sheet blank, then first sheet will be selected
  • \answer{text} add row to the spreadsheet
  • \savespreadsheet saves sheet to the ods file
  • environment exam all answers should be inside it, at end, it saves file content.xml in the current directory.

Note: there is some spurious space in definition of \answer, that I cannot find.

Now some sample file:

\documentclass{article}
\usepackage{lmodern,exams}
\begin{document}
\examspreadsheet{template.ods}{}

\begin{exam}{Test1}
\item Bla bla \answer{Test of special characters < > \& "}
\item The \answer{definition of entropy} states that \answer{$S = k_B
    \ln \Omega$}. 
\end{exam}
\savespreadsheet
\end{document}

Compile with 

lualatex --shell-escape  sample.tex

If you get error message in the console output like:

zip I/O error: Permission denied

zip error: Could not create output file (was replacing the original zip file)
Updating an ods file.
zip template.ods content.xml
 Return code:   15

then you have to change file permissions of the ods file to enable writing for other users, or simply run command

zip -r template.ods content.xml

And the result in openoffice calc:

enter image description here

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