问题

Question

下面显示了一个黑色的蛋形丘和一系列由模拟外部数据构建的“红云”蛋形丘。

\documentclass[pstricks,dvipsnames]{standalone}
\usepackage{pst-plot,filecontents,siunitx}

\begin{filecontents*}{test.data}
60      0
70      2
80      8
90      24
100     56
110     86 
120     110
130     120
\end{filecontents*}

\newpsstyle{mygrid}
{
    Dy=10,
    Dx=10,
    Ox=0,
    %tickwidth=1.2pt,
    subticksize=1,
    xsubticks=5,
    ysubticks=5,
    subtickcolor=lightgray,
    %subtickwidth=.8pt,
    xAxisLabel=\huge Mass (\si{\gram}),
    xAxisLabelPos={c,-7},
    yAxisLabel=\huge Cumulative Frequency,
    yAxisLabelPos={-13,c},
    llx=-2,
    lly=-2,
    urx=1,
    ury=1,  
}
\readdata{\mydata}{test.data}

\makeatletter
\pst@def{PreparePoints}<{%  on stack are [ x y x y ...
    counttomark /m exch def
    ] /DATA ED                 % save array
    m 2 div cvi 2 mod 0 gt     % odd or even pair of coordinates
      { 101 /Median ED } % odd
      { 101 /Median ED} % even
    ifelse
    /n 0 def
    [
    DATA length 2 div cvi { 
      DATA n get Median sub k mul Median add DATA n 1 add get 
      /n n 2 add def 
    } repeat
}>
\makeatother

\begin{document}
\begin{psgraph}[style=mygrid,xticksize=0 120,yticksize=0 200](0,0)(200,120){20cm}{20cm}
\multido{\r=-2.40+0.30}{17}{%
\pstVerb{/k \r\space def }%
\listplot[plotstyle=cspline,linecolor=red,linewidth=1pt,showpoints]{\mydata}}
\pstVerb{/k 1 def }%
\listplot[plotstyle=cspline,linecolor=black,linewidth=1pt,showpoints]{\mydata}
\end{psgraph}
\end{document}

我必须在Red-Cloud答案中对中位数 101（用我的眼睛粗略估计）进行硬编码，这样我才得到以下结果。

问题

如何动态计算中位数？

Answer 1

中位数计算的代码可以优化，但我今天没有时间：

\documentclass[pstricks,dvipsnames]{standalone}
\usepackage{pst-plot,filecontents,siunitx}

\begin{filecontents*}{test.data}
    60      0
    70      2
    80      8
    90      24
    100     56
    110     86 
    120     110
    130     120
\end{filecontents*}

\newpsstyle{mygrid}
{
    Dy=10,
    Dx=10,
    Ox=0,
    tickwidth=1.2pt,
    subticksize=1,
    xsubticks=2,
    ysubticks=2,
    subtickcolor=gray,
    subtickwidth=.8pt,
    xAxisLabel=\huge Mass (\si{\gram}),
    xAxisLabelPos={c,-7},
    yAxisLabel=\huge Cumulative Frequency,
    yAxisLabelPos={-12,c},
    llx=-2,
    lly=-2,
    urx=1,
    ury=1,  
}
\readdata{\mydata}{test.data}

\makeatletter
\pst@def{PreparePoints}<{%  on stack are [ x y x y ...
    counttomark /m exch def
    m 2 div cvi /n exch def
    ] /DATA exch def                 % save array
    DATA 1 get /yMin exch def DATA m 1 sub get /yMax exch def
    yMin yMax add 2 div /yMean exch def  
    0 2 m 2 sub {% get left x value
      /loopVar exch def
      DATA loopVar 1 add get yMean lt 
        { /x0 DATA loopVar get def  /y0 DATA loopVar 1 add get def } if
    } for
    m 1 sub -2 1 {% get right x value
      /loopVar exch def
      DATA loopVar get yMean gt 
        { /x1 DATA loopVar 1 sub get def  /y1 DATA loopVar get def } if
    } for
    x1 x0 sub y1 y0 sub div yMean y0 sub mul x0 add 
    /Median exch def Median ==
    /n 0 def
    [
    DATA length 2 div cvi { 
        DATA n get Median sub k mul Median add DATA n 1 add get 
        /n n 2 add def 
    } repeat
}>
\makeatother

\begin{document}
    \begin{psgraph}[style=mygrid,xticksize=0 120,yticksize=0 200](0,0)(200,120){15cm}{20cm}
        \multido{\rk=1.1+0.3,\iB=100+-10}{6}{%
            \pstVerb{/k \rk\space def }
            \listplot[plotstyle=cspline,linecolor=red!\iB,linewidth=2.4pt,showpoints]{\mydata}}
        \pstVerb{/k 1 def }
        \listplot[plotstyle=cspline,linecolor=black,linewidth=2.4pt,showpoints]{\mydata}
    \end{psgraph}

\end{document}