☰

使用 fillbetween 宏在两条曲线之间进行填充

tag-icon • tag-icon pgfplots fillbetween
使用 fillbetween 宏在两条曲线之间进行填充

我设法在不使用宏 fillbetween 的情况下为两条曲线限定的区域着色，因为指令\addplot[gray] fill between[of=F and G, soft clip={domain=0:4}];没有给出正确的绘图。怎么办？

\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{intersections}
\usepgfplotslibrary{fillbetween}
\begin{document}
\begin{tikzpicture}[
/pgf/declare function={f(\x)= (3.6*\x +2.4)*exp(-0.6*\x) -1.4;},
/pgf/declare function={g(\x)=4*\x^2 -4*\x +1;},
/pgf/declare function={f_1(\x)=-1*f(\x);},
/pgf/declare function={g_1(\x)=-1*g(\x);}]
\begin{axis}[
 restrict x to domain=-2:5, xmax=5, xmin=-1,
 restrict y to domain=-3:3, ymax=3, ymin=-3,
 x=1.25cm,
 y=1.25cm,
 axis x line =middle,
 axis y line =middle,
 tickwidth=0.15cm,
 axis on top=true,
 grid=both,
 axis line style =ultra thick,
 major tick style=black,
 xtick={0,...,4},
 ytick={-2,...,2},
 extra x ticks={-1,5},
 extra x tick label={\null},
 extra y ticks={-3,3},
 extra y tick label={\null},
 extra tick style={tick style={draw=none}},
 y tick label style={
       /pgf/number format/1000 sep={}
   },
 xlabel=$x$,ylabel=$y$,
 every axis x label/.style={
 at={(ticklabel* cs:1.01)},
 anchor=west,
 },
 every axis y label/.style={
 at={(ticklabel* cs:1.01)},
 anchor=south,
 },
 samples=2000,
 >=stealth,
 ]

 \addplot [draw=none, fill=gray, domain=0:4] {f(x)}\closedcycle;
 \addplot [draw=none, fill=white, domain=0:0.5] {g(x)}\closedcycle;
 \addplot [draw=none, fill=gray, domain=0:4] {f_1(x)}\closedcycle;
 \addplot [draw=none, fill=white, domain=0:0.5] {g_1(x)}\closedcycle;
 \addplot [ultra thick,domain=0:4,smooth] {f(x)};
 \addplot [ultra thick,domain=0:0.5,smooth] {g(x)};
 \addplot [ultra thick,domain=0:4,smooth,dashed] {f_1(x)};
 \addplot [ultra thick,domain=0:0.5,smooth,dashed] {g_1(x)};

 \draw[thick](4,{f(4)})--(4,{f_1(4)});
 \node [below left] at (0,0) {O};
 \end{axis}                  
 \end{tikzpicture}
 \end{document}

在此处输入图片描述

答案1

这是一个非常简单的方法：不是手动将两个函数拼凑在一起，而是将它们拼凑在参数图中，这样就没有问题了。这种方法的另一个优点是线连接看起来不错。（在您的示例中，线连接被粗轴覆盖，但一般来说这是一个问题。）

\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\usetikzlibrary{intersections}
\usepgfplotslibrary{fillbetween}
\begin{document}
\begin{tikzpicture}[
/pgf/declare function={f(\x)= (3.6*\x +2.4)*exp(-0.6*\x) -1.4;},
/pgf/declare function={g(\x)=4*\x^2 -4*\x +1;},
/pgf/declare function={f_1(\x)=-1*f(\x);},
/pgf/declare function={g_1(\x)=-1*g(\x);},
/pgf/declare function={F(\x)=ifthenelse(\x<4,f(\x),g(\x-4));},]
\begin{axis}[
 restrict x to domain=-2:5, xmax=5, xmin=-1,
 restrict y to domain=-3:3, ymax=3, ymin=-3,
 x=1.25cm,
 y=1.25cm,
 axis x line =middle,
 axis y line =middle,
 tickwidth=0.15cm,
 axis on top=true,
 grid=both,
 axis line style =ultra thick,
 major tick style=black,
 xtick={0,...,4},
 ytick={-2,...,2},
 extra x ticks={-1,5},
 extra x tick label={\null},
 extra y ticks={-3,3},
 extra y tick label={\null},
 extra tick style={tick style={draw=none}},
 y tick label style={
       /pgf/number format/1000 sep={}
   },
 xlabel=$x$,ylabel=$y$,
 every axis x label/.style={
 at={(ticklabel* cs:1.01)},
 anchor=west,
 },
 every axis y label/.style={
 at={(ticklabel* cs:1.01)},
 anchor=south,
 },
 samples=2000,
 >=stealth,
 ]

 \addplot [name path=f,ultra thick,domain=-0.5:4,smooth] ({abs(x)},
 {ifthenelse(x<0,g(-x),f(x))});
 \addplot [name path=f1,ultra thick,domain=-0.5:4,smooth,dashed] ({abs(x)},
 {ifthenelse(x<0,g_1(-x),f_1(x))});
 \addplot[gray] fill between[of=f and f1];
 \draw[thick](4,{f(4)})--(4,{f_1(4)});
 \node [below left] at (0,0) {O};
 \end{axis}                  
 \end{tikzpicture}
 \end{document}

在此处输入图片描述

答案2

本着完全公开的精神，我必须说，当你从 更改soft clip为{domain=0.01:0.5}时，{domain=0.0:0.5}解决方案就会停止工作，我实际上不明白原因

\documentclass[border=10pt]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{intersections}
\usepgfplotslibrary{fillbetween}
\pgfplotsset{compat=1.14}
\begin{document}
\begin{tikzpicture}[
  /pgf/declare function={f(\x)= (3.6*\x +2.4)*exp(-0.6*\x) -1.4;},
  /pgf/declare function={g(\x)=4*\x^2 -4*\x +1;},
  /pgf/declare function={f_1(\x)=-1*f(\x);},
  /pgf/declare function={g_1(\x)=-1*g(\x);}]
  \begin{axis}[
    restrict x to domain=-2:5, xmax=5, xmin=-1,
    restrict y to domain=-3:3, ymax=3, ymin=-3,
    x=1.25cm,
    y=1.25cm,
    axis x line =middle,
    axis y line =middle,
    tickwidth=0.15cm,
    axis on top=true,
    grid=both,
    axis line style =ultra thick,
    major tick style=black,
    xtick={0,...,4},
    ytick={-2,...,2},
    extra x ticks={-1,5},
    extra x tick label={\null},
    extra y ticks={-3,3},
    extra y tick label={\null},
    extra tick style={tick style={draw=none}},
    y tick label style={
      /pgf/number format/1000 sep={}
    },
    xlabel=$x$,ylabel=$y$,
    every axis x label/.style={
      at={(ticklabel* cs:1.01)},
      anchor=west,
    },
    every axis y label/.style={
      at={(ticklabel* cs:1.01)},
      anchor=south,
    },
    samples=200,
    >=stealth,
    ]

    \addplot [name path=F, ultra thick,domain=0:4,smooth] {f(x)};
    \addplot [name path=G, ultra thick,domain=0:0.5,smooth] {g(x)};

    \addplot [name path=F1, ultra thick,domain=0:4.0,smooth,dashed] {f_1(x)};
    \addplot [name path=G1, ultra thick,domain=0:0.5,smooth,dashed] {g_1(x)};

    \addplot[gray] fill between[of=F1 and G1, soft clip={domain=0.01:0.5}];
    \addplot[gray] fill between[of=F and G, soft clip={domain=0.01:0.5}];
    \addplot[gray] fill between[of=F1 and F, soft clip={domain=0.5:4.0}];

  \end{axis}                  
 \end{tikzpicture}
 \end{document}

在此处输入图片描述

相关内容