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线的圆形末端和节点的定位？

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线的圆形末端和节点的定位？

我正在尝试复制以下图像：

在此处输入图片描述

我目前的工作：

\documentclass{article}

%%for graphs
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
\usepgfplotslibrary{fillbetween}
%%end graph code

\begin{document}
\begin{tikzpicture}[scale=1]
\begin{axis}[
        axis x line=bottom,%need to change to bottom to put 0 in 
        axis y line=middle,
        x label style={at={(axis cs: 2.6, -0.12)},anchor=south},%rotate = degrees number can be used to rotate the label
        y label style={at={(axis cs:0, 2.5)},anchor=south},
        xtick={0, 1, 2}, %or {listofvalues, , },
        ytick={0, 1, 2},
        yticklabels={$0$, $1$, $2$},
        xticklabels={$0$, $1$, $2$},
        ymin=0,
        ymax=2.5,
        xmin=0,
        xmax=2.5,
        ylabel=$y$, 
        xlabel=$x$,
        area style,
        ]
    %thick lines
    \draw[draw = black, ultra thick] (axis cs: 0, 0) -- (axis cs: 0, 2);
    \draw[draw = black, ultra thick] (axis cs: 0.5, 0) -- (axis cs: 0.5, 1.5) node [above, right] {$y = 2 - x$};
    %y=0 label
    \node [below] at (axis cs: 0.5,0) {$y=0$};
    %line with label
    \addplot+[draw = black, ultra thick, name path = upper, domain=0:2] {2-x} node [midway, sloped, above, black] {$x + y = 2$};
    %node for labeling line
    \addplot+[draw = black, ultra thick, name path = lower, domain=0:2] {0};  
    %shading    
    \addplot[gray!40] fill between[of = upper and lower];
\end{axis}
\end{tikzpicture}
\end{document}

在此处输入图片描述

主要问题是节点标签没有出现并且位置不正确，而且我不确定如何获得线的圆形末端。

谢谢您的帮助 - 如果这些问题已经在其他地方得到解答，请见谅。

答案1

您需要应用clip=false并放置circle节点。您还拥有above, right有效的right——我认为您的意思是above right。

在此处输入图片描述

另外，如果您想对垂直线使用不同的颜色（如上所示），最好在环境外面绘制，axis以便正确显示填充的圆：

在此处输入图片描述

代码：

\documentclass{article}

%%for graphs
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
\usepgfplotslibrary{fillbetween}
%%end graph code

\begin{document}
\begin{tikzpicture}[scale=1]
\begin{axis}[
        axis x line=bottom,%need to change to bottom to put 0 in 
        axis y line=middle,
        x label style={at={(axis cs: 2.6, -0.12)},anchor=south},%rotate = degrees number can be used to rotate the label
        y label style={at={(axis cs:0, 2.5)},anchor=south},
        xtick={0, 1, 2}, %or {listofvalues, , },
        ytick={0, 1, 2},
        yticklabels={$0$, $1$, $2$},
        xticklabels={$0$, $1$, $2$},
        ymin=0,
        ymax=2.5,
        xmin=0,
        xmax=2.5,
        ylabel=$y$, 
        xlabel=$x$,
        area style,
        clip=false,
        ]
    %y=0 label
    \node [below] at (axis cs: 0.5,0) {$y=0$};
    %line with label
    \addplot+[draw = black, ultra thick, name path = upper, domain=0:2] {2-x} 
        node [midway, sloped, above, black] {$x + y = 2$};
    %node for labeling line
    \addplot+[draw = black, ultra thick, name path = lower, domain=0:2] {0};  
    %shading    
    \addplot[gray!40] fill between[of = upper and lower];
    %thick lines
    \draw[draw = black, ultra thick] (axis cs: 0, 0) -- (axis cs: 0, 2);
    \draw[draw = red, ultra thick] (axis cs: 0.5, 0) -- (axis cs: 0.5, 1.5) 
        node [draw=red, circle, fill=red, inner sep=2pt, pos=0]  {}
        node [draw=red, circle, fill=red, inner sep=2pt, pos=1]  {}
        node [above right] {$y = 2 - x$};
\end{axis}
\end{tikzpicture}
\end{document}

代码：在axis环境外部绘制：

\documentclass{article}

%%for graphs
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
\usepgfplotslibrary{fillbetween}
%%end graph code

\begin{document}
\begin{tikzpicture}[scale=1]
\begin{axis}[
        axis x line=bottom,%need to change to bottom to put 0 in 
        axis y line=middle,
        x label style={at={(axis cs: 2.6, -0.12)},anchor=south},%rotate = degrees number can be used to rotate the label
        y label style={at={(axis cs:0, 2.5)},anchor=south},
        xtick={0, 1, 2}, %or {listofvalues, , },
        ytick={0, 1, 2},
        yticklabels={$0$, $1$, $2$},
        xticklabels={$0$, $1$, $2$},
        ymin=0,
        ymax=2.5,
        xmin=0,
        xmax=2.5,
        ylabel=$y$, 
        xlabel=$x$,
        area style,
        clip=false,
        ]
    %y=0 label
    \node [below] at (axis cs: 0.5,0) {$y=0$};
    %line with label
    \addplot+[draw = black, ultra thick, name path = upper, domain=0:2] {2-x} 
        node [midway, sloped, above, black] {$x + y = 2$};
    %node for labeling line
    \addplot+[draw = black, ultra thick, name path = lower, domain=0:2] {0};  
    %shading    
    \addplot[gray!40] fill between[of = upper and lower];
    %thick lines
    \draw[draw = black, ultra thick] (axis cs: 0, 0) -- (axis cs: 0, 2);

    \coordinate (TOP) at (axis cs: 0.5, 1.5);
    \coordinate (BOT) at (axis cs: 0.5, 0);
\end{axis}
    \draw[draw = red, ultra thick] (BOT) -- (TOP) 
        node [draw=red, circle, fill=red, inner sep=2pt, pos=0]  {}
        node [draw=red, circle, fill=red, inner sep=2pt, pos=1]  {}
        node [above right] {$y = 2 - x$};
\end{tikzpicture}
\end{document}

答案2

一种方法是为圆圈添加两个额外的节点并定义相对于它们的文本。请注意，要在轴外绘制，您必须打开clip=false。

\documentclass{article}

%%for graphs
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
\usepgfplotslibrary{fillbetween}
%%end graph code

\begin{document}
\begin{tikzpicture}[scale=1]
\begin{axis}[
        axis x line=bottom,%need to change to bottom to put 0 in 
        axis y line=middle,
        x label style={at={(axis cs: 2.6, -0.12)},anchor=south},%rotate = degrees number can be used to rotate the label
        y label style={at={(axis cs:0, 2.5)},anchor=south},
        xtick={0, 1, 2}, %or {listofvalues, , },
        ytick={0, 1, 2},
        yticklabels={$0$, $1$, $2$},
        xticklabels={$0$, $1$, $2$},
        ymin=0,
        ymax=2.5,
        xmin=0,
        xmax=2.5,
        ylabel=$y$, 
        xlabel=$x$,
        area style,
        clip=false,%<-- This option needs to be added
        ]
    %thick lines
    \draw[draw = black, ultra thick] (axis cs: 0, 0) -- (axis cs: 0, 2);
    \node[circle,fill] at (axis cs:0.5,1.5) (a) {};%<---- Here is for drawing the circle
    \draw[draw = black, ultra thick] (axis cs: 0.5, 0) -- (axis cs: 0.5, 1.5)
        node[anchor=south west] at (a.north east) {$y = 2 - x$};
    %y=0 label
    \node[circle,fill] at (axis cs:0.5,0) (b) {};%<---- Here is for drawing the circle
    \node[anchor=north] at (b.south) {$y=0$};
    %line with label
    \addplot+[draw = black, ultra thick, name path = upper, domain=0:2] {2-x} node [midway, sloped, above, black] {$x + y = 2$};
    %node for labeling line
    \addplot+[draw = black, ultra thick, name path = lower, domain=0:2] {0};  
    %shading    
    \addplot[gray!40] fill between[of = upper and lower];
\end{axis}
\end{tikzpicture}
\end{document}

在此处输入图片描述

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