在 LaTeX 中绘制 2 个方向图

Question

绘制这两个图形的 LateX 代码是什么？

Answer 1

您可以使用以下内容作为起始示例：

\documentclass[border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,decorations.markings}

\begin{document}
    \begin{tikzpicture}[%
        decoration={
            markings,% switch on markings
            mark=% actually add a mark
            at position .7
            with
                {
                    \arrow [line width=1pt] {<},
                }
        }]

    \filldraw  (0,0) circle [radius=1pt];

    \draw [postaction={decorate}] 
        (0,0) to [out=45, in=-45, distance= 2cm] node [right] {$x$} (0,0);
    \draw [postaction={decorate}]
        (0,0) to [out=45, in=-45, distance=-2cm] node [left]  {$y$} (0,0);

    \end{tikzpicture}
\end{document}

Answer 2

经过一些修改：

\documentclass[border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,decorations.markings}

\begin{document}
    \begin{tikzpicture}

    \filldraw  (0,0) circle [radius=1pt];
    \filldraw  (0,2) circle [radius=1pt];

    \draw [postaction={decorate},
        decoration={markings,% switch on markings
            mark=% actually add a mark
            at position .6
            with
                {
                    \arrow [line width=1pt] {<},
                }
        }]
        (0,2) to [out=0, in=0, distance= 0.75cm] node [left] {$x$} (0,0);

    \draw [postaction={decorate},
        decoration={markings,% switch on markings
            mark=% actually add a mark
            at position .55
            with
                {
                    \arrow [line width=1pt] {<},
                }
        }]
        (0,2) to [out=0, in=0, distance= 1.5cm] node [right] {$y$} (0,0);

    \draw [postaction={decorate},
        decoration={markings,% switch on markings
            mark=% actually add a mark
            at position .48
            with
                {
                    \arrow [line width=1pt] {>},
                }
        }]
        (0,2) to [out=0, in=0, distance=-.75cm] node [right] {$x$} (0,0);

    \draw [postaction={decorate},
        decoration={markings,% switch on markings
            mark=% actually add a mark
            at position .48
            with
                {
                    \arrow [line width=1pt] {>},
                }
        }]
        (0,2) to [out=0, in=0, distance=-1.5cm] node [left] {$y$} (0,0);

    \end{tikzpicture}
\end{document}