TikZ array of coordinates

Question

How can I define an array of coordinates in TikZ? Consider the following:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
  \begin{tikzpicture}
    \newcommand{\vertA}{{(0,0),(1,0),(2,0)}}
    \foreach \i in {0,1,2} {
      \coordinate (V\i) at ($\vertA[\i]$);
    }
  \end{tikzpicture}
\end{document}

Compiling with pdflatex gives the error:

Runaway argument?
\vertA [\i ]$); \pgffor@endhook \ifx \pgffor@assign@after@code \pgfutil@empty \
ETC.
! File ended while scanning use of \tikz@cc@parse@factor.

\foreach \i in {0,1,2} {\coordinate (V\i) at (\i,0);} – hpesoj626 Mar 20 '13 at 17:46 — hpesoj626, Mar 20 '13 at 17:46
The second coordinate is not always zero.. – Håkon Hægland Mar 20 '13 at 17:57 — Håkon Hægland, Mar 20 '13 at 17:57

score 11 · Accepted Answer · answered Mar 20 '13 at 17:42

11

I would go about this differently: Instead of looping over the indices and then accessing the members of the \vertA array, you can loop directly over the coordinate array and use the count=<macro name> function of \foreach.

I couldn't get the \coordinate (<name>) at (<coordinate>) command to accept a macro as its coordinate, so I went with the \coordinate [at=<coordinate macro>] approach instead:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
  \begin{tikzpicture}
    \newcommand{\vertA}{(0,0),(1,0),(2,3)}
    \foreach \coord [count=\i] in \vertA {
      \coordinate [at=\coord, name=A\i];
    }
    \draw (A1) -- (A2) -- (A3);
  \end{tikzpicture}
\end{document}

answered Mar 20 '13 at 17:42

Jake

232,450

Great! This works.. – Håkon Hægland Mar 20 '13 at 17:55
Why does not \coordinate (A\i) at \coord; work here? – Håkon Hægland Mar 23 '13 at 08:48
Don't know. Something with the parser. You can say \coordinate [at=\coord] (A\i);, though, if you want – Jake Mar 23 '13 at 08:51

TikZ array of coordinates

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