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如何引用“newcommand”中定義的參數？

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如何引用“newcommand”中定義的參數？

我在做什麼：
我想畫一張圖（如下圖）來說明一些區間收縮到一條線上的節點。
間隔

首先，我定義一個newcommand有三個參數的 for 間隔（即 \op）：起點、終點和名稱。然後，繪製一條線（或一條鏈）。最後，將區間與直線上對應的節點連接起來。整個程式碼是：（筆記：您也可以閱讀和修改共享程式碼共享乳膠在接受任何答案之前。

\documentclass{article}
\usepackage[utf8]{inputenc}

\usepackage{tikz}
\usetikzlibrary{calc, chains}

\title{Reference Arguments in Newcommand}
\author{hengxin}
\date{31 December 2013}

\begin{document}
\begin{tikzpicture}[]

% new command: inverval
\newcommand{\op}[3] % #1: start point; #2: end point; #3: interval name
{
  \coordinate (start) at #1;    % start point
  \coordinate (end) at #2;  % end point
  \coordinate (mid) at ($0.5*#1 + 0.5*#2 + (0,0.8cm)$);

  \draw[ultra thick, blue, |-|] (start) -- (end); % draw the interval
  \node (#3) [font = \huge] at (mid) {#3};  % attach the operation name
}

% define three intervals
\op{(0,2)}{(2,2)}{$a$};
\op{(4,3)}{(6,3)}{$b$};
\op{(7,2)}{(10,2)}{$c$};

% contract them into single nodes in a line (or a chain)
\begin{scope}[font = \huge, start chain = schedule, node distance = 3.0cm, every     join/.style = {very thick, ->, red}]
  \foreach \opi in {a, b, c}
    \node (\opi) [circle, draw, on chain, join, label = {[] below : $\opi$}] {};
\end{scope}

% connect interval and its corresponding node in the line
\begin{scope}[cedge/.style = {->, dashed, draw, thick}]
  \draw [cedge] (0,2) to (a);
  \draw [cedge] (2,2) to (a);

  \draw [cedge] (4,3) to (b);
  \draw [cedge] (6,3) to (b);

  \draw [cedge] (7,2) to (c);
  \draw [cedge] (10,2) to (c);
\end{scope}

\end{tikzpicture}
\end{document}

我想做的事：
正如您所看到的，在最後一步（連接區間及其在行中的相應節點）中，我已經硬編碼了每個區間的起點和終點的座標，如\draw [cedge] (0,2) to (a); \draw [cedge] (2,2) to (a);。這無疑是乏味且容易出錯的。所以，

newcommand有沒有一些優雅的方法可以讓我在不進行硬編碼的情況下引用每個區間的兩個點（作為 的參數）？

答案1

在\op命令中，您可以命名間隔的每個限制（#3作為名稱的一部分）。

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{calc, chains}
\begin{document}
\begin{tikzpicture}
  % new command: inverval
  \newcommand{\op}[3]{ % #1: start point; #2: end point; #3: operation name
    \coordinate (start #3) at #1;   % start point
    \coordinate (end #3) at #2; % end point

    \draw[ultra thick, blue, |-|] (start #3) -- (end #3) % draw the interval
    node[pos=.5,above=8mm,font=\huge, text=black] {$#3$}; % attach the operation name
  }
  % define three intervals
  \op{(0,2)}{(2,2)}{a};
  \op{(4,3)}{(6,3)}{b};
  \op{(7,2)}{(10,2)}{c};
  % contract them into single nodes in a line (or a chain)
  \begin{scope}[font=\huge, start chain=schedule, node distance=3.0cm,
    every join/.style={very thick, ->, red}]
    \foreach \opi in {a, b, c} {
      \node [circle,draw,on chain,join,label={[]below:$\opi$}] (\opi) {};
    }
  \end{scope}
  % connect interval and its corresponding node in the line
  \begin{scope}[cedge/.style = {->, dashed, draw, thick}]
    \foreach \interval in {a,b,c}{
      \draw [cedge] (start \interval) to (\interval);
      \draw [cedge] (end \interval) to (\interval);
    }
  \end{scope}
\end{tikzpicture}
\end{document}

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