答案1
您应该提供 MWE!无论如何,下面是我的代码。
\documentclass[tikz,border=5mm]{standalone}
\begin{document}
\begin{tikzpicture}[line width=1.2pt,
n/.style={circle,draw=#1,text=#1,font=\bfseries\sffamily},
arr/.style={-latex,shorten >=1pt,#1}]
\path
(0,0) node[n=black] (L1) {2}
+(0:1) node[n=black] (R1) {1}
++(-90:1.5) node[n=blue] (L2) {1}
+(0:1) node[n=blue] (R2) {2}
++(-90:1.5) node[n=red!70!black] (L3) {2}
+(0:1) node[n=red!70!black] (R3) {1};
\draw[arr] (L1)--(L2) coordinate[pos=.4](A);
\fill (A) circle(1mm) node[left=1mm]{$X_2$};
\draw[arr] (R1)--(R2) coordinate[pos=.4](B);
\draw[arr] (B)--(L2);
\fill (B) circle(1mm) node[right=1mm]{$X$};
\draw[arr=blue] (L2)--(L3) coordinate[pos=.4] (C);
\fill[blue] (C) circle(1mm) node[left=1mm]{$R_1$};
\draw[arr=blue] (R2)--(R3) coordinate[pos=.4](D);
\draw[arr=blue] (D)--(L3);
\draw[arr=blue] (C)--(R2);
\fill[blue] (D) circle(1mm) node[right=1mm]{$R_2$};
\draw[arr] (L3)--+(-90:.8);
\draw[arr] (R3)--+(-90:.8);
\end{tikzpicture}
\end{document}
答案2
一个练习,使用@Black Mild 的答案作为 OP 的 MWE:
\documentclass[tikz,border=5mm]{standalone}
\usetikzlibrary{arrows.meta,
chains,
positioning}
\begin{document}
\begin{tikzpicture}[
node distance = 12mm and 9mm,
start chain = A going below,
dot/.style = {circle, fill=#1, inner sep=2pt, outer sep=0pt},
cn/.style = {circle, draw=#1, semithick,
text=#1, minimum size=1.2em, inner sep=2pt,
on chain=A},
every edge/.style = {draw=#1, -{Triangle[angle=60:2pt 3]},semithick, shorten >=1pt}
]
\node[cn=black] {2}; % A-1
\node[cn=blue] {1};
\node[cn=red!70!black] {2}; % A-3
%
\draw (A-1) edge[black] node (d1) [dot=black,label=left:$X_2$] {} (A-2)
(A-2) edge[blue] node (d2) [dot=blue, label=left:$R_1$] {} (A-3)
(A-3) edge[black] ++ (0,-1)
;
%%
\node[cn=black,
right=of A-1] {1}; % A-4
\node[cn=blue] {2};
\node[cn=red!70!black] {1}; % A-6
%
\draw (A-4) edge[black] node (d3) [dot=black,label=right:$X_1$] {} (A-5)
(A-5) edge[blue] node (d4) [dot=blue, label=right:$R_2$] {} (A-6)
(A-6) edge[black] ++ (0,-1);
%% cross lines
\draw (d3) edge (A-2)
(d2) edge (A-5)
(d4) edge (A-3);
\end{tikzpicture}
\end{document}