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pgfplots：两个图之间的水平距离

tag-icon • tag-icon tikz-pgf pgfplots
pgfplots：两个图之间的水平距离

我正在尝试使用 pgfplots 绘制下图：

阴谋

该图是用 matlab 生成的。

我可以用 pgfplots 轻松绘制两条曲线，但我不知道如何添加带有 0.3dB 标记的垂直线。也许有可能提取 y=10^-1 处两个图的 x（SNR）的（插值）值。应该提到的是，只有 20、22、24、26、28、30 和 32 dB 的 y 值可用。

这是我当前的 TeX 代码（绘图数据与 matlab 图片不完全吻合，但想法是一样的）：

\documentclass[a4paper, ngerman]{scrreprt}
\usepackage{color}
% predefined colors
\definecolor{color1}{rgb}{0.44706,0.44706,0.44706}%
\definecolor{color2}{rgb}{0.09412,0.34902,0.66275}%
\definecolor{color3}{rgb}{0.92941,0.17647,0.18039}%
\definecolor{color4}{rgb}{0.00000,0.54902,0.27843}%
% include pgfplots 
\usepackage{pgfplots}
\usepackage{pgfplotstable}
% custom settings
\pgfplotsset{compat=1.3}
\pgfplotsset{every axis/.append style={line width=1pt}}       % line widths
\pgfplotsset{                                                 % customized size (x1.3)
  mysize/.style={
  /pgfplots/width=312pt,
  /pgfplots/height=269pt,
  /pgfplots/max space between ticks=35}
}
\pgfplotsset{                                                 % fer plot config
  ferplotcfg/.style={
    /pgfplots/xmin  = 20,
    /pgfplots/xmax  = 32,
    /pgfplots/ymin  = 10e-3, 
    /pgfplots/ymax  = 10e-1,
    /pgfplots/grid  = both,
    minor grid style = {dashed},
    major grid style = {dashed}}
}
\pgfplotsset{                                                 % reference curve cfg
  line_ref/.style={
    color1,
    /tikz/smooth,
    /tikz/mark=none,
    /tikz/style={dashed}}
}
\pgfplotsset{                                                 % reference curve cfg
  line_1/.style={
    color2,
    /tikz/smooth,
    /tikz/mark=o}
}

\begin{document}

\centering
\begin{tikzpicture}
  \begin{axis} [
    title = FER Performance,
    legend entries = {Reference, Fixed Point},
    xlabel = {SNR (dB)}, ylabel = {FER},
    ferplotcfg, mysize, ymode = log,
    ]
    \addplot[line_ref] table[x=snr, y=reference, col sep=comma, row sep=crcr] {
      snr,matlab_full_sim_fxp,reference\\
      20,0.93682,0.92946\\
      22,0.76335,0.73643\\
      24,0.39312,0.3622\\
      26,0.11584,0.10718\\
      28,0.036743,0.029785\\
      30,0.012695,0.010864\\
      32,0.0064697,0.0039063\\}; 
    \addplot[line_1] table[x=snr, y=matlab_full_sim_fxp, col sep=comma, row sep=crcr] {
      snr,matlab_full_sim_fxp,reference\\
      20,0.93682,0.92946\\
      22,0.76335,0.73643\\
      24,0.39312,0.3622\\
      26,0.11584,0.10718\\
      28,0.036743,0.029785\\
      30,0.012695,0.010864\\
      32,0.0064697,0.0039063\\}; 
  \end{axis}
\end{tikzpicture}
\end{document}

答案1

实现此目的的一种方法是结合pgfplots：将节点放置在特定的 x 位置上和将单位转换为坐标适用于 x 坐标，但不适用于 y 坐标首先将坐标放置在指定的 y 位置，然后计算差值：

\documentclass{standalone}
% include pgfplots 
\usepackage{pgfplots}
\usetikzlibrary{intersections, calc}
% custom settings
\pgfplotsset{compat=newest}
\pgfplotsset{                                                 % customized size (x1.3)
  mysize/.style={
  /pgfplots/width=312pt,
  /pgfplots/height=269pt,
  /pgfplots/max space between ticks=35}
}
\pgfplotsset{                                                 % fer plot config
  ferplotcfg/.style={
    /pgfplots/xmin  = 20,
    /pgfplots/xmax  = 32,
    /pgfplots/ymin  = 10e-3, 
    /pgfplots/ymax  = 10e-1,
    /pgfplots/grid  = both,
    %minor grid style = {dashed},
    %major grid style = {dashed}
    }
}
\pgfplotsset{                                                 % reference curve cfg
  line_ref/.style={
    color1,
    /tikz/smooth,
    /tikz/mark=none,
    /tikz/style={dashed}}
}
\pgfplotsset{                                                 % reference curve cfg
  line_1/.style={
    color2,
    /tikz/smooth,
    /tikz/mark=o}
}

\makeatletter
\def\parsenode[#1]#2\pgf@nil{%
    \tikzset{label node/.style={#1}}
    \def\nodetext{#2}
}

\tikzset{
    add node at y/.style 2 args={
        name path global=plot line,
        /pgfplots/execute at end plot visualization/.append={
                \begingroup
                \@ifnextchar[{\parsenode}{\parsenode[]}#2\pgf@nil
            \path [name path global = position line #1]
                ({axis cs:0,#1}-|{rel axis cs:0,0}) --
                ({axis cs:0,#1}-|{rel axis cs:1,1});
            \path [
                name intersections={
                    of={plot line and position line #1},
                    name=intersection
                },
            ] (intersection-1)
            node [label node] {\nodetext};
            \endgroup
        }
    }
}


\begin{document}

\centering
\begin{tikzpicture}
  \begin{axis} [
    ferplotcfg, mysize, ymode = log,
    ]
    \addplot[black, add node at y={0.1}{[coordinate, name=pointA]}] table[x=snr, y=reference, col sep=comma, row sep=crcr] {
      snr,matlab_full_sim_fxp,reference\\
      20,0.93682,0.92946\\
      22,0.76335,0.73643\\
      24,0.39312,0.3622\\
      26,0.11584,0.10718\\
      28,0.036743,0.029785\\
      30,0.012695,0.010864\\
      32,0.0064697,0.0039063\\}; 
    \addplot[blue, add node at y={0.1}{[coordinate, name=pointB]}] table[x=snr, y=matlab_full_sim_fxp, col sep=comma, row sep=crcr] {
      snr,matlab_full_sim_fxp,reference\\
      20,0.93682,0.92946\\
      22,0.76335,0.73643\\
      24,0.39312,0.3622\\
      26,0.11584,0.10718\\
      28,0.036743,0.029785\\
      30,0.012695,0.010864\\
      32,0.0064697,0.0039063\\};
      \draw let \p1=(pointA), \p2=(pointB) in (pointA) -- (pointB) node [pos=0, left] {%
        \pgfplotsconvertunittocoordinate{x}{\x1}%
        \pgfplotscoordmath{x}{datascaletrafo inverse to fixed}{\pgfmathresult}%
        \edef\valueA{\pgfmathresult}%
        \pgfplotsconvertunittocoordinate{x}{\x2}%
        \pgfplotscoordmath{x}{datascaletrafo inverse to fixed}{\pgfmathresult}%
        \pgfmathparse{\pgfmathresult - \valueA}%
        \pgfmathprintnumber{\pgfmathresult} dB
        };
  \end{axis}
\end{tikzpicture}
\end{document}

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