答案1
没有tikz-cd
,抱歉。
\documentclass[tikz,border=3.14mm]{standalone}
\begin{document}
\begin{tikzpicture}
\foreach \X [count=\Y]in {1,2,3,4,5,r-2,r-1,r}
{\unless\ifnum\Y=5
\draw[<-,shorten <=5pt] (0,0) -- node[auto] {$a_{\X}$}(135-\Y*45:pi)
node[circle,fill,inner sep=2pt,label=135-45*\Y:$\X$]{};
\fi}
\end{tikzpicture}
\end{document}