使用 \pgfmathifthenelse 放置节点

Question

我正在尝试使用\pgfmathifthenelse命令将节点放置在图表中tikz，但仍然出现此错误：

“不完整 \iffalse”

这是我的代码：

    \begin{tikzpicture}

    \def \n {4}
    \def \hradius {2cm}
    \def \vradius {1.2cm}
    \def \nradius {0cm}
    \def \lengths {3,4,6}
    \def \degree {3}
    \node (u) at (0,{2*\vradius}) {$\bullet$};
    \node (v) at (0,{-2*\vradius}) {$\bullet$};
    \node at (0,{2.2*\vradius}) {$u$};
    \node at (0,{-2.2*\vradius}) {$v$};
    \draw[>=latex] (v.center) -- (u.center) node [midway,left]{{$1$}};
    \foreach [count=\i, evaluate=\i as \k] \s in \lengths {
        \pgfmathparse{\s-1}
        \edef \l {\pgfmathresult}
        \pgfmathparse{\k-2}
        \def \xtmp {\pgfmathresult}
        \pgfmathparse{\xtmp+1}
        \edef \xfactor {\pgfmathresult}
        \pgfmathparse{\pgfmathifthenelse{\xtmp=0}{\xfactor {\xtmp}}\pgfmathresult
        \edef \xfinal {\pgfmathresult}
        \foreach \i in {1,...,\l}{
            \pgfmathparse{1/\s}
            \def \inverse {\pgfmathresult}
            \node (\s\i) at ({(\k-2)*\hradius},{((4*\vradius)*\inverse*\i)-2*\vradius}) {\k};
        }
    }

    \end{tikzpicture}

有人知道问题出在哪里吗？

Answer 1

一些问题：

1. 您在带有 的行处缺少一个括号pgfmathifthenelse。
2. 可以重写所有命令以内联设置变量，而不是使用\pgfmathresult.\pgfmathparse这样做，但您可以使用\pgfmathsetmacro<VARIABLE>{<CODE>}

因此，你可以\pgfmathifthenelse像这样修复重写：

\pgfmathsetmacro\xfinal{(\xtmp==0?(\xfactor):\xtmp)}

确实

\pgfmathsetmacro\xfinal{(<TEST>?(<TRUE>):<FALSE>)}

输出

代码

\documentclass[margin=10pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\def\n{4}
\def\hradius{2cm}
\def\vradius{1.2cm}
\def\nradius{0cm}
\def\lengths{3,4,6}
\def\degree{3}

\node (u) at (0,{2*\vradius}) {$\bullet$};
\node (v) at (0,{-2*\vradius}) {$\bullet$};
\node at (0,{2.2*\vradius}) {$u$};
\node at (0,{-2.2*\vradius}) {$v$};
\draw[>=latex] (v.center) -- (u.center) node [midway,left]{{$1$}};
\foreach [count=\i, evaluate=\i as \k] \s in \lengths {%
    \pgfmathsetmacro\l{\s-1}
    \pgfmathsetmacro\xtmp{\k-2}
    \pgfmathsetmacro\xfactor{\xtmp+1}
    \pgfmathsetmacro\xfinal{(\xtmp==0?(\xfactor):\xtmp)}
    \foreach \i in {1,...,\l}{%
        \pgfmathsetmacro\inverse{1/\s}
        \node (\s\i) at ({(\k-2)*\hradius},{((4*\vradius)*\inverse*\i)-2*\vradius}) {\k};
    }
}
\end{tikzpicture}
\end{document}