使用Tikz的Latex节点图

节点图也可以使用tikz环境绘制。

你可以在顶点周围绘制圆, 也可以直接使用它们。用于样式的命令与框图或流程图中的命令不同。绘制顶点的命令由node命名, 绘制边缘的命令由edge命名。

Latex中使用的命令主要来自常用词, 这些词可以在代码中轻松理解和实现。

在开始形状之前, 你需要提及一些环境。你必须仅在以下环境中包括你的文本和命令, 如下所示：

\documentclass[10pt]{article} % you can change the point size according to the requirements
\usepackage{xcolor} % package crucial to implement colors
\usepackage{tikz} % package used for the tikz
\begin{document}
\begin{tikzpicture} % tikz environment 
....................
\end{tikzpicture}
\end{document}

通过使用x轴和y轴上的点, 可以绘制任何形状。下面给出了使用Tikz的乳胶中使用的常见形状：

• 圈

画圆的命令是\ draw（1, 1）circle（1）;

此处, （1, 1）是x和y轴上的点, 而（1）是圆的半径。

上面的圆圈的输出看起来像下面的图像：

• 三角形

下面给出了用于绘制三角形的命令：

\path[draw] (2, 2) -- (3, 3)--(4, 2)--cycle;

输出：

你可以根据需要更改x和y轴的点的位置。

你还可以使用以下命令填充三角形内部的颜色：

\path[fill=green] (2, 2) -- (3, 3) -- (4, 2) -- cycle;

输出：

要增加三角形的宽度, 可以使用以下命令：

\path[draw, line width=3pt] (2, 2) -- (3, 3)--(4, 2)--cycle;

输出：

你还可以使用以下命令在三角形内部绘制颜色图案：

\path[clip, draw] (2, 2)--(3, 3)--(4, 2)--cycle;
\path[fill=blue!40] (3, 2.7) circle (.7);

输出：

你也可以使用任何形状代替三角形。

• 椭圆

要绘制椭圆, 需要使用以下命令：

\draw[fill=pink] (0, 0)
ellipse (30pt and 22pt);

这里, （0, 0）是原点, 而30pt和22pt是绘制椭圆的尺寸。

输出：

你也可以相应地混合两种颜色。

该示例的命令写为：

\draw[fill=blue!50!white] (0, 0)
ellipse (30pt and 22pt);

输出：

使用这种方法, 你可以根据自己的选择创建任何形状。

让我们从节点图开始。

下面给出了创建简单节点图的代码：

\documentclass{article}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}
  [scale=.9, auto=center, every node/.style={circle, fill=blue!20}] % here, node/.style is the style pre-defined, that will be the default layout of all the nodes. You can also create different forms for different nodes.
  
  \node (a1) at (1, 2) {1};
  \node (a2) at (2, 5)  {2}; % These all are the points where we want to locate the vertices. You can create your diagram first on a rough paper or graph paper; then, through the points, you can create the layout. Through the use of paper, it will be effortless for you to draw the diagram on Latex.
  \node (a3) at (3, 7)  {3};
  \node (a4) at (3, 2.5) {4};
  \node (a5) at (5, 6)  {5};
  \node (a6) at (5, 3)  {6};
  \node (a7) at (7, 5)  {7};

  \draw (a1) -- (a2); % these are the straight lines from one vertex to another
  \draw (a2) -- (a3);
  \draw (a2) -- (a4);
  \draw (a4) -- (a6);
  \draw (a3) -- (a5);
  \draw (a6) -- (a7);
  \draw (a5) -- (a7);

\end{tikzpicture}

\end{document}

输出：

你还可以将图的边缘弯曲一定角度。

下面给出了创建具有弯曲边缘的节点图的代码：

\documentclass[10pt]{article}
\usepackage{color}
\usepackage{tikz}

% the settings of tikz is used for the optimization of the graphs
\usetikzlibrary{shapes, arrows, calc, arrows.meta, fit, positioning} % these are the parameters passed to the library to create the node graphs
\tikzset{
    -Latex, auto, node distance =1.5 cm and 1.3 cm, thick, % node distance is the distance between one node to other, where 1.5cm is the length of the edge between the nodes
    state/.style ={ellipse, draw, minimum width = 0.9 cm}, % the minimum width is the width of the ellipse, which is the size of the shape of vertex in the node graph
    point/.style = {circle, draw, inner sep=0.18cm, fill, node contents={}}, bidirected/.style={Latex-Latex, dashed}, % it is the edge having two directions
    el/.style = {inner sep=2.5pt, align=right, sloped}
}
\begin{document}

\begin{tikzpicture}
    % a is the name of the node and A is the text inside the node/vertex
    \node[state] (a) at (0, 0) {$A$}; % here, state signifies that the shape of the node will be the shape declared in the above state/.style command.

    % you can mention any location such as right, left, above, below, etc.
   
    \node[state] (b) [right =of a] {$B$};
    \node[state] (c) [below =of b] {$C$};
    \path (a) edge (b); % it is the path of the edge from one node to another

    % Bidirected edge
    \path[bidirected] (a) edge[bend left=60] (b); % this is the basic command in this code. It is used to draw the curved edge with a certain angle. You can change the angle according to the requirements.
    
    \path (a) edge (c);
     \path[bidirected] (a) edge[bend right=60] (c);
     \draw (b) -- (c);
    
\end{tikzpicture}
\end{document}

输出：