Sort database with datatool

Question

I use the datatool package to read CSV files and print them as tables. Before printing I want to sort the rows. The problem is that the file was written with R and some rows contain normal numbers (like 0.124) and some contain numbers in scientific format (e.g. 1.23e-4).

How can I tell datatool to interpret both values as numerical and sort accordingly?

Answer 1

You don't need datatool, at least for this work. You can sort the data without showing scientific notation and make a beautiful table just inserting some R code in your LaTeX file and compile with Sweave (or knitr).

To do in this way, you LaTeX document must have a .Rnw extension and compile in two steps with:

R CMD Sweave MWE.Rnw % this make MWE.tex 
pdflatex MWE.tex     % this make MWE.pdf

If you file have crossreferences, as usual, you must repeat the pdflatex compilation. If only a pdflatex run is needed, you can make all with R:

R CMD Sweave --pdf  MWE.Rnw % this make the MWE.pdf

(Note: RStudio understand .Rnw files and make all these steps with one click.)

This is the example: (the external data source is typed verbatim, you can copy this part and save as text.csv to test the code):

\documentclass[spanish,11pt]{article}
\begin{document}
\setlength{\parindent}{0pt}
\SweaveOpts{concordance=TRUE}

Raw file \texttt{text.csv}: 

\begin{verbatim}
minor, big
0.34552, 25
1.23e-4, 34
5.45677223344, 12
0.000001, 99
\end{verbatim}

R display in plain text by default 
<<RawTable,echo=F>>=
a  <- read.table("text.csv", header=TRUE, sep=",")
a
@
R display ordered and rounded:
<<RawTable,echo=F>>=
round(a[order(a$minor), ],4)
@
In R also but with  \LaTeX{} style
<<Mytable,echo=F,results=tex>>=
library(xtable)
xtable(a[order(a$minor), ], caption="My ordered table",digits=4)
@
\end{document}