CODEWITHSUNDEEP
latexcoordinatestikz
flawr
flawr

Reputation: 11628

How to get the defined coordinates of nodes?

In the following example I would expect the vertical lines of the rectangles to be aligned, but for some reason they are not. I assume this is because not the actual coordinates of the nodes are used, but they in include some kind of offset. I also tried using .base for each of the nodes in the rectangle command, but it didn't solve that problem.

How can I access the actual coordinates I defined in the nodes?

\documentclass[a4paper]{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
\node (d) at (0, 7) [anchor=west] {$D_i$};
\node (c) at (0, 5) [anchor=west] {$C^j$}; 
\node (b) at (0, 3) [anchor=west] {$B_k$}; 
\node (a) at (0, 1) [anchor=west] {$A$};
\draw ($(a)+(-1, -1)$) rectangle ($(b)+(1,1)$);
\draw ($(c)+(-1, -1)$) rectangle ($(d)+(1,1)$);
\end{tikzpicture}
\end{document}

Update: I realize the alignment problem can be solved by defining the cooridnates first like in the following code, but I'd be still interested to hear how to extract the actual coordinates from a node.

\documentclass[a4paper]{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
\coordinate (d) at (0, 7);
\coordinate (c) at (0, 5);
\coordinate (b) at (0, 3);
\coordinate (a) at (0, 1);
\node  at (d) [anchor=west] {$D_i$};
\node  at (c) [anchor=west] {$C^j$}; 
\node  at (b) [anchor=west] {$B_k$}; 
\node  at (a) [anchor=west] {$A$};
\draw ($(a)+(-1, -1)$) rectangle ($(b)+(1,1)$);
\draw ($(c)+(-1, -1)$) rectangle ($(d)+(1,1)$);
\end{tikzpicture}
\end{document}

enter image description here

Upvotes: 1

Views: 1291

Answers (1)

samcarter_is_at_topanswers.xyz
samcarter_is_at_topanswers.xyz

Reputation: 38967

  • instead of manually calculating the corners of the rectangle with ($(a)+(-1, -1)$) etc, you could use the corners of nodes with (a.south west) etc.

  • to avoid misalignment, make sure all your nodes have the same size by specifying a big enough minimum width and height

  • it might be more convenient to position the nodes below each other with the positioning library

\documentclass[a4paper]{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[every node/.style={minimum width=2cm,minimum height=2cm}]
\node (d) at (0, 7)   {$D_i$};
\node[below of=d] (c) {$C^j$}; 
\node[below of=c,anchor=north] (b) {$B_k$}; 
\node[below of=b] (a) {$A$};
\draw (a.south west) rectangle (b.north east);
\draw (c.south west) rectangle (d.north east);
\end{tikzpicture}
\end{document}

enter image description here

Upvotes: 1

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