在 tikz 中用 x 和其他符号标记网格

Question

我是 tikz 新手。我有以下网格：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\usetikzlibrary{patterns}
\usetikzlibrary{shapes}
\usetikzlibrary{plotmarks}

\newcommand{\nvar}[2]{
    \newlength{#1}
    \setlength{#1}{#2}
}

\nvar{\dx}{1cm}

\begin{document}
\begin{tikzpicture}
    % fill outside cells
    \fill [orange!40] (-1,-1) rectangle ( 3, 0); 
    \fill [orange!40] (-1, 2) rectangle ( 3, 3); 
    \fill [orange!40] (-1, 0) rectangle ( 0, 2); 
    \fill [orange!40] ( 2, 0) rectangle ( 3, 2); 
% pressure cells
\draw [semithick][help lines, step=\dx] (-1,-1) grid ( 3, 3);
\draw [thin,dashed][help lines, step=.5*\dx] (-1,-1) grid ( 3, 3); 
\draw [red,thick] ( 0, 0) rectangle ( 2, 2);
\draw [red,thick] (-1,-1) rectangle ( 3, 3);

\end{tikzpicture}
\end{document}

我想注释网格的边缘以生成在 tikz 中看起来像这样的图片：

Answer 1

像这样吗？

\documentclass[tikz]{standalone}

\newcommand{\nvar}[2]{
    \newlength{#1}
    \setlength{#1}{#2}
}

\nvar{\dx}{1cm}

\begin{document}
\begin{tikzpicture}
    \path [draw=red, thick, fill=orange!40, even odd rule,] (-1,-1) rectangle (3,3) (0,0) rectangle (2,2);
    \draw [semithick][help lines, step=\dx] (-1,-1) grid ( 3, 3);
    \draw [thin,dashed][help lines, step=.5*\dx] (-1,-1) grid ( 3, 3);
    \foreach \i in {0,...,2}
      \foreach \j in {.5, 1.5}
      {
        \node [green] at (\i,\j) {$\times$};
        \node [black!80] at (\j,\i) {$\otimes$};
      }
\end{tikzpicture}
\end{document}

初始命令使用两个矩形替换了 4 个矩形和边框的绘制even odd rule。（我只是觉得这是一个巧妙的技巧，最近发现它在 tikz 中有效，而不仅仅是 metapost。;) 所以我忍不住……）

为了进行注释，我使用两个循环遍历变量，将它们嵌套起来，并使用每个值对坐标进行迭代x和对坐标进行迭代。基本上，tikz 将使用所有可能的/y对运行这些循环，从而节省输入时间。\i\j

Answer 2

因为为什么不呢？：P

\documentclass[tikz]{standalone}
\usetikzlibrary{plotmarks}
\begin{document}
\begin{tikzpicture}
\def\dx{1cm}\def\mylista{}\def\mylistb{}
\foreach \x in {0,1,2}{
  \foreach \y in {.5,1.5}{
     \xdef\mylista{\mylista (\x,\y)}\xdef\mylistb{\mylistb (\y,\x)}
  }
}
\draw[thick,red,double distance between line centers=\dx,double=orange!40] (-0.5,-0.5) rectangle (2.5,2.5);
\draw [semithick][help lines, step=\dx] (-1,-1) grid ( 3, 3);
\draw [thin,dashed][help lines, step=.5*\dx] (-1,-1) grid ( 3, 3); 
\draw --plot [only marks,mark=otimes] coordinates \mylistb;
\draw --plot [only marks,mark=x,mark options={color=green}] coordinates \mylista;
\end{tikzpicture}
\end{document}

Answer 3

在环境的末尾tikzpicture（就在 之前\end{tikzpicture}）插入下面的代码。

\foreach \a in {.5,1.5}{
 \foreach \b in {0,1,2}{
   \node at (\a,\b){$\otimes$};
   \node[green] at (\b,\a){$\times$};
 }
}