如何使用 PGFPlots 绘制分数数据？

Question

我们可以轻松绘制以下数据：

\RequirePackage{filecontents} 
\begin{filecontents}{data.dat}
X P $Q_B$ $Q_C$ $Q_D$
1 A1  2   6   7
2 A2  3   65  87
3 A3  1   45  65
4 A4  4   54  45
5 A5  6   56  34
6 A6  8   34  23
7 A7  9   45  45
8 A8  13  23  56
9 A9  4.6 6   87
10 A10 4   56  89
\end{filecontents}

\documentclass{article}
 \usepackage{pgfplotstable}
 \usepackage{pgfplots}
 \pagestyle{empty}
 \begin{document}

 \pgfplotstabletypeset[columns/P/.style={string type}]{data.dat}

  \vspace{1cm}

 \begin{tikzpicture}
  \begin{axis}[
   xlabel=Q Series,
   ylabel=P Values,
   xticklabels from table={data.dat}{P},xtick=data]
   \addplot[blue,thick,mark=square*] table [y=$Q_B$,x=X]{data.dat};
   \addlegendentry{$Q_B$ series}
   \addplot[red,thick,mark=square*] table [y=$Q_C$,x=X]{data.dat};
  \addlegendentry{$Q_C$ series}
  \addplot[black,dashed,thick,mark=square*]  table [y=$Q_D$,x=X]{data.dat};
  \addlegendentry{$Q_D$ series}
  \end{axis}
  \end{tikzpicture}

  \end{document}   

问题：
有没有办法绘制如下所示的分数数据：

X P $Q_B$ $Q_C$ $Q_D$
1 A1  1/2   1/6   1/7
2 A2  1/3   65  87
3 A3  1   1/45  65
4 A4  4   54  45
5 A5  6   56  34
6 A6  8   1/4^3  23
7 A7  9   45  45
8 A8  13  23  56
9 A9  1/4.6  6   87
10 A10 4   56  89

Answer 1

您可以使用y expr和相应的进一步语法来做到这一点。

    \begin{filecontents*}{data.dat}
        X  P   $Q_B$ $Q_C$ $Q_D$
        1  A1  1/2   1/6   1/7
        2  A2  1/3   65    87
        3  A3  1     1/45  65
        4  A4  4     54    45
        5  A5  6     56    34
        6  A6  8     1/4^3 23
        7  A7  9     45    45
        8  A8  13    23    56
        9  A9  1/4.6 6     87
        10 A10 4     56    89
    \end{filecontents*}
\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
    \pgfplotsset{compat=1.3}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        xlabel=Q Series,
        ylabel=P Values,
        xtick=data,
        xticklabels from table={data.dat}{P},
    ]
        \addplot [blue,thick,mark=square*] table [
            x=X,
%            % this worked so far, ...
%            y=$Q_B$,
            % ... but now we have to use this and it works
            y expr=\thisrow{$Q_B$},
        ]{data.dat};
            \addlegendentry{$Q_B$ series}
        \addplot [red,thick,mark=square*] table [
            x=X,
            y expr=\thisrow{$Q_C$},
        ]{data.dat};
            \addlegendentry{$Q_C$ series}
        \addplot [black,dashed,thick,mark=square*] table [
            x=X,
            y expr=\thisrow{$Q_D$},
        ]{data.dat};
            \addlegendentry{$Q_D$ series}
    \end{axis}
\end{tikzpicture}
\end{document}