pgfplots 宏：x filter/.code={\pgfmathparse{#1/1000000}\pgfmathresult} 不适用于 csv 文件

Question

我想要 x 轴在 MHz 范围内，因此我想要使用命令：

• x filter/.code={\pgfmathparse{#1/1000000}\pgfmathresult}

但什么都没发生。我正在使用 lualatex 进行图像编译。CSV 文件是从实验室仪器获得的，我不想每次生成新文件时都更改它。我尝试按照 4.22 节完成这项工作pgfplots 手册（跳过或更改坐标 - 过滤器）。

我的 MNWE 是：

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.17}
\usepgflibrary{luamath}

\usepackage{siunitx}

\begin{document}
\begin{tikzpicture}
  \begin{semilogyaxis}[
    % title={ Quartz Crystals Resonance Frequencies },
    xlabel={ Frequency [\si{\MHz}] },
    ylabel={ Impedance [\si{\ohm}] },  
    xmajorgrids=true,
    ymajorgrids=true,
    yminorgrids=true,
    grid style=solid,
    tick scale binop=\times,           % page 347 man. ver. 1.15
    cycle list name = color list,      % page 212 man. ver. 1.15
    ]
      \addplot 
        table[
          x index=0,  y index=3, 
          /pgf/number format/read comma as period,
          skip first n=31, 
          x filter/.code={\pgfmathparse{#1/1000000}\pgfmathresult},
          col sep=semicolon,
        ] {tikz003_data.csv};
      \legend{Impedance}
    \end{semilogyaxis}
  \end{tikzpicture}
\end{document}

CSV文件的相关内容如下：

Frequency (Hz);Trace 1: Impedance: Real (Ω);Trace 1: Impedance: Imaginary (Ω);Trace 1: Impedance: Magnitude (Ω)
11000000;37,52887681;-5113,935907;5114,073609
11000977,04;37,60450902;-5115,102842;5115,241068
11001954,08;37,43878572;-5114,644072;5114,781094
11002931,12;36,8805983;-5113,873122;5114,006109
11003908,16;37,27322288;-5112,017215;5112,153099
11004885,2;36,9557493;-5111,327511;5111,461107
11005862,24;38,75948108;-5111,658528;5111,805474
11006839,28;37,43056578;-5112,087105;5112,224136
11007816,32;39,73565309;-5110,324112;5110,478593
11008793,36;37,00349591;-5110,290774;5110,424743
11009770,4;38,17700954;-5111,313222;5111,455795
11010747,44;36,67828736;-5109,138839;5109,270493
11011724,47;35,88358107;-5104,672947;5104,799068

Answer 1

这是（原则上）一个使用表数据的简单任务。有关详细信息，请查看代码中的注释。

% used PGFPlots v1.17
\documentclass[border=5pt]{standalone}
\usepackage{siunitx}
\usepackage{pgfplots}
    \pgfplotsset{compat=1.17}
\begin{document}
\begin{tikzpicture}
    \begin{semilogyaxis}[
        xlabel={Frequency in \si{\MHz}},
        ylabel={Impedance in \si{\ohm}},
        xmajorgrids=true,
        ymajorgrids=true,
        yminorgrids=true,
        grid style=solid,
        cycle list name=color list,
    ]
        \addplot table[
%            % replace this ...
%            x index=0,
            % ... with this where you can manipulate table data "as you like"
            x expr={\thisrowno{0}/1e6},
            y index=3,
%            % because with commas as decimal separators an unexpected error
%            % occurred I replaced all commas with periods which made it work
%            % (this seems to be a bug)
%            /pgf/number format/read comma as period,
            col sep=semicolon,
        ] {
            Frequency (Hz);Trace 1: Impedance: Real (Ω);Trace 1: Impedance: Imaginary (Ω);Trace 1: Impedance: Magnitude (Ω)
            11000000;37.52887681;-5113.935907;5114.073609
            12000000.05;37.60450902;-5115.102842;18.5
            13000000;35.88358107;-5104.672947;380000
        };
        \legend{Impedance}
    \end{semilogyaxis}
\end{tikzpicture}
\end{document}