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在 tikz/gnuplot 图中突出显示坐标

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在 tikz/gnuplot 图中突出显示坐标

我想在图表上放置一个坐标tikz。gnuplot该怎么做？

坐标图

我希望图形与小红点重叠，并且我希望这个点稍微大一些。

\documentclass{article}

\usepackage{pgfplots}
\usepackage[heightrounded]{geometry}
\usepackage[miktex]{gnuplottex}

\begin{document}

\subsubsection{P-waarde bij de chi-kwadraattoets}

\textbf{\textit{Let op!}} Deze paragraaf is geen stof die je moet weten, maar alleen ter verduidelijking!

\begin{figure}[h]
\begin{center}
\begin{tikzpicture}
  \begin{axis}[%
    xlabel = $\chi ^2$,
    ylabel = $P\left(\chi ^2 (5) \geq \chi ^2\right)$,
    samples = 200,
   xtick={4,5,6,...,15},ytick={0,.05,.1,.15,.2,.25,.3,.35,.4,.45,.5},
    restrict y to domain = 0.045:0.5,
    domain = 5:15,
  every axis y label/.style={at=(current axis.above origin),anchor=south},
 every axis x label/.style={at=(current axis.right of origin),anchor=west},
  height=8cm, width=8cm,
axis lines*=left]
    \foreach \k in {5} {%
      \addplot+[mark={}] gnuplot[raw gnuplot] {%
    isint(x)=(int(x)==x);
    log2 = 0.693147180559945;
    cchisq(x,k)=k<=0||!isint(k)?1/0:x<0?0.0:igamma(0.5*k,0.5*x);
    set xrange [ 5 : 15.0000 ];
    set yrange [ 0 : 1.0000 ];
        samples=200;
        plot 1-cchisq(x,\k)};
}
  \end{axis}
\end{tikzpicture}
\end{center}
\caption{Kansfunctie (Chi-kwadraat CDF) om een bepaalde waarde van $\chi ^2$ te vinden}
\end{figure}
\end{document}

答案1

有一种可能性是：

\documentclass{article}
\usepackage[heightrounded]{geometry}
\usepackage{pgfplots}
\usepackage[miktex]{gnuplottex}
\usetikzlibrary{intersections,backgrounds}

\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\begin{document}

\subsubsection{P-waarde bij de chi-kwadraattoets}

\textbf{\textit{Let op!}} Deze paragraaf is geen stof die je moet weten, maar alleen ter verduidelijking!

\begin{figure}
\centering
\begin{tikzpicture}
\begin{axis}[%
  xlabel = $\chi ^2$,
  ylabel = $P\left(\chi ^2 (5) \geq \chi ^2\right)$,
  samples = 200,
  xtick={4,5,6,...,15},
  ytick={0,.05,.1,.15,.2,.25,.3,.35,.4,.45,.5},
  restrict y to domain = 0.045:0.5,
  domain = 5:15,
  every axis y label/.style={at=(current axis.above origin),anchor=south},
  every axis x label/.style={at=(current axis.right of origin),anchor=west},
  height=8cm, 
  width=8cm,
  axis lines*=left
  ]
  % a vertical ``invisible'' line to get the coordinates of the dot
  \path[name path=line] (axis cs:2.5,0) -- (axis cs:2.5,0.5);
  \foreach \k in {5} {%
    \addplot+[mark={},name path=graph] gnuplot[raw gnuplot] {%
      isint(x)=(int(x)==x);
      log2 = 0.693147180559945;
      cchisq(x,k)=k<=0||!isint(k)?1/0:x<0?0.0:igamma(0.5*k,0.5*x);
      set xrange [ 5 : 15.0000 ];
      set yrange [ 0 : 1.0000 ];
      samples=200;
      plot 1-cchisq(x,\k)};
  }
  % we get the coordinates of the intersection of the graph and the invisible line
  % the resulting point is called interp
  \path[name intersections={of=line and graph, by={interp}}];
  % we place the dot behind the graph
  \begin{pgfonlayer}{background}
    \node[draw=red,circle,inner sep=1.7pt] at (interp) {};
  \end{pgfonlayer}
  % we draw the lines connecting the dot with the axes 
  \draw (axis cs:2.5,0) -- (interp);
  \draw (interp) -- ({axis cs:0,0}|-interp);
  \end{axis}
\end{tikzpicture}
\caption{Kansfunctie (Chi-kwadraat CDF) om een bepaalde waarde van $\chi ^2$ te vinden}
\end{figure}

\end{document}

在此处输入图片描述

点附近的放大图像：

在此处输入图片描述

答案2

这是一个可能的解决方案，通过从 x 坐标向上绘制intersections来tikzlibrary确定交点，然后沿 y 轴水平绘制一条线。

在此处输入图片描述

代码

\documentclass{article}
\usepackage[margin=0.5cm,papersize={12cm,14cm}]{geometry}
\usepackage{pgfplots}
\usepackage[heightrounded]{geometry}
\usepackage[miktex]{gnuplottex}
\usetikzlibrary{intersections}

\begin{document}

\newcommand*{\ShowIntersection}[2]{ % borrowed from http://tex.stackexchange.com/a/21409/34618
\fill
    [name intersections={of=#1 and #2, name=i, total=\t}]
    [red, opacity=1, every node/.style={above left, black, opacity=1}]
    \foreach \s in {1,...,\t}{(i-\s) circle (2pt)};
}

\subsubsection{P-waarde bij de chi-kwadraattoets}

\textbf{\textit{Let op!}} Deze paragraaf is geen stof die je moet weten, maar alleen ter verduidelijking!

\begin{figure}[h]
\begin{center}
\begin{tikzpicture}
  \begin{axis}[%
    xlabel = $\chi ^2$,
    ylabel = $P\left(\chi ^2 (5) \geq \chi ^2\right)$,
    samples = 200,
   xtick={4,5,6,...,15},ytick={0,.05,.1,.15,.2,.25,.3,.35,.4,.45,.5},
    restrict y to domain = 0.045:0.5,
    domain = 5:15,
  every axis y label/.style={at=(current axis.above origin),anchor=south},
 every axis x label/.style={at=(current axis.right of origin),anchor=west},
  height=8cm, width=8cm,
axis lines*=left]
    \foreach \k in {5} {%
      \addplot+[mark={},name path global=a] gnuplot[raw gnuplot] {%
    isint(x)=(int(x)==x);
    log2 = 0.693147180559945;
    cchisq(x,k)=k<=0||!isint(k)?1/0:x<0?0.0:igamma(0.5*k,0.5*x);
    set xrange [ 5 : 15.0000 ];
    set yrange [ 0 : 1.0000 ];
        samples=200;
        plot 1-cchisq(x,\k)};
}
\draw [red,name path global=b] (axis cs: 5.8,0)--(axis cs: 5.8,0.35);  % draw a line to find intersection
\ShowIntersection{a}{b}                                                % show intersection
\draw [red] (i-1) -| (axis cs: 0,1);                                   % draw a line from intersection point to y axis
  \end{axis}
\end{tikzpicture}
\end{center}
\caption{Kansfunctie (Chi-kwadraat CDF) om een bepaalde waarde van $\chi ^2$ te vinden}
\end{figure}
\end{document}

答案3

您可以简单地在绘图上画线，只需在绘图之前画线即可使线条显示在背景中。此外，您还必须将该axis on top=true选项包含在轴选项中。

\draw[gray, line width=0.2pt] (axis cs:5.6655,0) -- (axis cs:5.6655,0.34) -- (axis cs:0,0.34);
\draw[red] (axis cs:5.6655,0.34) circle[radius=2pt];

这是放大 2400% 后的效果（线条更窄且呈灰色，以匹配轴的刻度）。

并且缩放至 100％。

完整代码：

\documentclass{article}

\usepackage{pgfplots}
\usepackage[heightrounded]{geometry}
\usepackage[miktex]{gnuplottex}

\begin{document}

\subsubsection{P-waarde bij de chi-kwadraattoets}

\textbf{\textit{Let op!}} Deze paragraaf is geen stof die je moet weten, maar alleen ter verduidelijking!

\begin{figure}[h]
\begin{center}
\begin{tikzpicture}
    \begin{axis}[%
        xlabel = $\chi ^2$,
        ylabel = $P\left(\chi ^2 (5) \geq \chi ^2\right)$,
        samples = 200,
        xtick={4,5,6,...,15},ytick={0,.05,.1,.15,.2,.25,.3,.35,.4,.45,.5},
        restrict y to domain = 0.045:0.5,
        domain = 5:15,
        every axis y label/.style={at=(current axis.above origin),anchor=south},
        every axis x label/.style={at=(current axis.right of origin),anchor=west},
        height=8cm, width=8cm,
        axis lines*=left,
        axis on top=true]
            \draw[gray, line width=0.2pt] (axis cs:5.6655,0) -- (axis cs:5.6655,0.34) -- (axis cs:0,0.34);
            \draw[red] (axis cs:5.6655,0.34) circle[radius=2pt];
            \foreach \k in {5} {%
                \addplot+[mark={}] gnuplot[raw gnuplot] {%
                    isint(x)=(int(x)==x);
                    log2 = 0.693147180559945;
                    cchisq(x,k)=k<=0||!isint(k)?1/0:x<0?0.0:igamma(0.5*k,0.5*x);
                    set xrange [ 5 : 15.0000 ];
                    set yrange [ 0 : 1.0000 ];
                    samples=200;
                    plot 1-cchisq(x,\k)
                };
            }
    \end{axis}
\end{tikzpicture}
\end{center}
\caption{Kansfunctie (Chi-kwadraat CDF) om een bepaalde waarde van $\chi ^2$ te vinden}
\end{figure}
\end{document}

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