Csdrhrt

I found yesterday this beautiful simple code:

documentclass{article}

usepackage{pgfplotstable}

usepackage{pgfplots}

pagestyle{empty}

begin{document}



%pgfplotstabletypeset{data.dat}



vspace{1cm}



begin{tikzpicture}

begin{axis}[

  xlabel=Q Series,

  ylabel=P Values]

addplot table [y=P, x=$Q_A$]{data.dat};

addlegendentry{$Q_A$ series}

addplot table [y=P, x=$Q_B$]{data.dat};

addlegendentry{$Q_B$ series}

addplot table [y=P, x=$Q_D$]{data.dat};

addlegendentry{$Q_D$ series}

end{axis}

end{tikzpicture}



end{document}

which works well with the external file

P $Q_A$ $Q_B$ $Q_D$

10 5 7 12

8 8 10 18

6 12 16 28

Yet, if I have more comlicated numbers in the file, for example

P $Q_A$ $Q_B$ $Q_D$

10 14.2*10^2 7 12

8 8 10 18

6 12 16 28

the code crashes.

How do I have to adapt the code or data to work?

Thx in advance

You can replace *10^ by e

P $Q_A$ $Q_B$ $Q_D$

10 14.2e2 7 12

8 8 10 18

6 12 16 28

You can load the data in a macro and then preprocess the data. I'm assuming here that your values are in a format the fpeval from expl3/xfp can handle (but your example value is rather large compared to the rest, so the plot looks odd):

documentclass{article}

usepackage{pgfplotstable}

usepackage{pgfplots,xfp}

pagestyle{empty}

begin{document}



pgfplotstableread{data.dat}{data}

pgfplotstablecreatecol[create col/expr={fpeval{thisrow{$Q_A$}}}]{$Q_A$}data

vspace{1cm}



begin{tikzpicture}

begin{axis}[

  xlabel=Q Series,

  ylabel=P Values]

addplot table [y=P, x=$Q_A$]{data};

addlegendentry{$Q_A$ series}

addplot table [y=P, x=$Q_B$]{data};

addlegendentry{$Q_B$ series}

addplot table [y=P, x=$Q_D$]{data};

addlegendentry{$Q_D$ series}

end{axis}

end{tikzpicture}



end{document} 

You only need to tell pgfplots that these are expressions. That is, instead of

addplot table [y=P, x=$Q_A$]{data.dat};

you only need

addplot table [y=P, x expr=thisrow{$Q_A$}]{data.dat};

MWE:

documentclass{article}

usepackage{filecontents}

begin{filecontents*}{data.dat}

P $Q_A$ $Q_B$ $Q_D$

10 14.2*10^2 7 12

8 8 10 18

6 12 16 28

end{filecontents*}

%usepackage{pgfplotstable}

usepackage{pgfplots}

pgfplotsset{compat=1.16}

pagestyle{empty}

begin{document}



%pgfplotstabletypeset{data.dat}



vspace{1cm}



begin{tikzpicture}

begin{axis}[

  xlabel=Q Series,

  ylabel=P Values]

addplot table [y=P, x expr=thisrow{$Q_A$}]{data.dat};

addlegendentry{$Q_A$ series}

addplot table [y=P,  x expr=thisrow{$Q_B$}]{data.dat};

addlegendentry{$Q_B$ series}

addplot table [y=P,  x expr=thisrow{$Q_D$}]{data.dat};

addlegendentry{$Q_D$ series}

end{axis}

end{tikzpicture}

end{document}