Drawing paths with TikZ from a DB with DataTool

Question

I have written this code and it works:

...
\DTLsetseparator{;}
\DTLloaddb[noheader]{DBcurva}{Curvas.csv}
\begin{tikzpicture}
\foreach \columna in {1,3,...,\DTLcolumncount{DBcurva}}{
\edef\listaPuntos{}
    \pgfmathtruncatemacro{\columnasig}{1+\columna} 
    \foreach \fila in {1,2,...,\DTLrowcount{DBcurva}}
    {
      \DTLgetvalue{\cX}{DBcurva}{\fila}{\columna}
      \DTLgetvalue{\cY}{DBcurva}{\fila}{\columnasig}
      \xdef\listaPuntos{(\cX,\cY) -- \listaPuntos}
    }
    \draw \listaPuntos cycle;
  }
\end{tikzpicture}
...

This reads a CSV file called "Curvas.csv". The columns are coordinates of points on curves (X1,Y1,X2,Y2,X3,Y3,X4,Y4..). The code draws all the curves in the file (initially I don't know how many there are) without problems.

Is there a better way (I can't separate each curve in different files)?

Answer 1

You could use pgfplots to loop through the columns in your datafile and draw the curves:

\documentclass{minimal}

\usepackage{pgfplots}

\begin{document}
\begin{tikzpicture}

\begin{axis}[every plot/.style={no markers},cycle list name=linestyles]
\pgfplotstableread[col sep=comma] {testdata.csv}\data % Save the CSV to a macro
\pgfplotstablegetcolsof{\data} % Get the number of columns n
\pgfmathparse{\pgfplotsretval-2} % Calculate column index Xn = n-2
\let\xmax\pgfmathresult

\foreach \x in {0,2,...,\xmax} {
    \pgfmathadd{\x}{1} % Offset one to get Y column index
    \let\y\pgfmathresult
    \addplot+[no markers,line width=2pt] table [x index=\x,y index=\y] \data;
}
\end{axis}

\end{tikzpicture}
\end{document}

testdata.csv:

X1,Y1,X2,Y2,X3,Y3,X4,Y4
0,0,0,1,0,2,0,3
4,2,5,1,6,6,6,0
8,3,10,4,10,1,10,10