foreach 循环中的节点锚点

Question

我需要根据符号更改节点的锚点。例如，如果符号为“-”，则锚点为“北”，否则为“南”。为此，我使用以下方法实现了该函数\def：

    \def\side#1{%
        \ifnum#1=-1%
        north%
        \else%
        south%
        \fi%
    }

该解决方案有效，但不一致。我能以某种方式实现它吗TikZ？这个问题甚至可能是全球性的。如何定义一个不返回数值而是返回锚点的函数？也许有一个更好/更紧凑的解决方案。

下面的 MWE

---

\documentclass[tikz]{standalone}

\begin{document}

\begin{tikzpicture}
    
    \node[draw] (A) at (-1,0) {};
    \node[draw] (B) at (1,0) {};
    
    \def\side#1{%
        \ifnum#1=-1%
        north%
        \else%
        south%
        \fi%
    }
    
    \foreach [evaluate=\i as \j using int(-1*\i)] \i in {-1, 1}
    {
        \draw[->] (A.\side{\i}) -- (B.\side{\j}) ; 
    } 
    
\end{tikzpicture}

\end{document}

Answer 1

第一个tikzpicture是你的，第二个似乎纯粹基于 TikZ：

\documentclass[tikz]{standalone}

\begin{document}

\begin{tikzpicture}
    
    \node[draw] (A) at (-1,0) {};
    \node[draw] (B) at (1,0) {};
    
    \def\side#1{%
        \ifnum#1=-1%
        north%
        \else%
        south%
        \fi%
    }
    
    \foreach [evaluate=\i as \j using int(-1*\i)] \i in {-1, 1}
    {
        \draw[->] (A.\side{\i}) -- (B.\side{\j}) ; 
    } 
    
\end{tikzpicture}


\begin{tikzpicture}
    
    \node[draw] (A) at (-1,0) {};
    \node[draw] (B) at (1,0) {};
    
    
    
    \foreach [evaluate=\i as \j using int(-1*\i)] \i in {90, 270}
    {
        \draw[->] (A.{\i}) -- (B.{\j}) ; 
    } 
    
\end{tikzpicture}

And the third

\begin{tikzpicture}
    
    \node[draw] (A) at (-1,0) {};
    \node[draw] (B) at (1,0) {};
    
    
    
    \foreach [evaluate=\i as \j using int(-1*\i)] \i in {-1, 1}
    {
        \draw[->] (A.{180+90*\i}) -- (B.{180+90*\j}) ; 
    }



\end{tikzpicture}

\end{document}