Input numbers from file

Question

I have numbers I need to put into my text in latex. The only possibility I know is using \input. So I put every single number in its own file. E.g. the file foo.dat contains 6.062843465325870040e-01 (I checked for trailing white spaces).

The first problem that appears is, that latex apparently puts a space after \input. So My number is \input{foo.dat}. yields

My number is 6.062843465325870040e-01 .

Note the unwanted space before the dot ..

---

The next problem is, that I obviously want properly formatted numbers. So I use siunits' \num. But \num{\input{foo.dat}} yields an error.

How can I fix this, or are there better solutions (without generating the properly formatted latex code as a file).

---

I considered https://stackoverflow.com/questions/29078107/insert-values-from-a-file-in-a-latex-document for my solution so far.

Answer 1

\unskip is your friend.

% arara: pdflatex
\RequirePackage{filecontents}
\begin{filecontents*}{foo.dat}
  6.062843465325870040e-01
\end{filecontents*}

\documentclass{article}

\begin{document}
My number is
  \textit{\input{foo.dat}\unskip}.
\end{document}

For usage with siunitx you might want to use the catchfile package:

% arara: pdflatex
\begin{filecontents*}{foo.dat}
  6.062843465325870040e-01
\end{filecontents*}

\documentclass{article}
\usepackage{siunitx}
\usepackage{catchfile}

\begin{document}
My number is
  \CatchFileDef{\foonum}{foo.dat}{}%
  \num\foonum.
\end{document}

If you have to do this very often it might be useful to wrap this process into a macro.

% arara: pdflatex
\begin{filecontents*}{foo.dat}
  6.062843465325870040e-01
\end{filecontents*}

\documentclass{article}
\usepackage{siunitx}
\usepackage{catchfile}

\newcommand*\OutputFileNum[2][\num]{%
  \CatchFileDef{\tempnum}{#2}{}%
  #1{\tempnum}%
}

\begin{document}
My number is \OutputFileNum{foo.dat}.
\end{document}

Answer 2

You wrote:

I have numbers I need to put into my text in latex. The only possibility I know is using \input. So I put every single number in its own file.

Another solution would consist of defining macros, named (say) \numA, \numB, etc, as follows

\newcommand\numA{6.062843465325870040e-01}
\newcommand\numB{3.141592653589793238e-00}

in the preamble and to use them in the body of the text as follows:

My first number is \numA.

If you want to apply some formatting, e.g., employ "thousands separators", load the siunitx package and write

My second number is \num{\numB}.

A full MWE (minimum working example):

\documentclass{article}
\usepackage{siunitx} % for '\num' macro
\newcommand\numA{6.062843465325870040e-01}
\newcommand\numB{3.141592653589793238}
\begin{document}
My first number is \numA.

My second number is \num{\numB}.
\end{document}

Answer 3

A easy way to store numbers (as many as you want in a single file) and retrieve single numbers can be done with LaTeX + R integration via knitr. Better, you can do any math with these numbers in the same document. If you do not know what on earth I'm talking about, just install Rstudio and R, save the both files below in the same testing directory, open test.Rnw with Rstudio and click on the "Compile PDF".

test.dat

3.037494573458934585e-04
6.062843465325870040e-01
9.331454567567567675e-05

test.Rnw

\documentclass{article}
\begin{document}
<<loaddata,echo=F,comment="">>=
mynumbers <-read.csv(file="test.dat",header=F)
x <- formatC(mynumbers$V1[2], format = "e", digits = 18)
@
My first  number is \Sexpr{mynumbers$V1[1]}.\par
My second number is \Sexpr{mynumbers$V1[2]}.\par 
My third  number is \Sexpr{mynumbers$V1[3]}.\par 
\bigskip
<<changeoptions,echo=F>>=
options(scipen=2,digits=19)
@
My second number roughly is \Sexpr{round(mynumbers$V1[2],2)}, 
more precisely  \Sexpr{round(mynumbers$V1[2],5)}.\par
My second number is \Sexpr{mynumbers$V1[2]}.\par
My second number is \Sexpr{x}.\par 
\end{document}

Result: