Why can't I draw with tikz nodes generated by loops with multiple variables?

Question

Why can't I draw lines between tikz nodes generated by loops with multiple variables?

I have a bunch of nodes, some of which I want to connect with a sequence of arrows. The notes are numbered, and I've tried to store some more data as well; in my minimal example below I've stored coordinates.

I found a way to create the notes. My problem is that I can't seem to use them to draw. The following example compiles:

\begin{tikzpicture}
\foreach \k in {0,1,2} 
\node (\k) at (\k,\k*\k-2*\k) {\k};
\def\Data{
  3 / 2  / 1,
  4 / 1  / 2,
  5 / 2  / 3}
\foreach \a / \x / \y in \Data 
\node (\a) at (\x,\y) {\a};

\draw (0) -- (2);
%\draw (3) -- (4);
\foreach \note  [remember=\note as \lastnote (initially {(0)})] in {(1),(2)} \draw[->] \lastnote -- \note;
% \foreach \note  [remember=\note as \lastnote (initially {(3)})] in {(4),(5)} \draw[->] \lastnote -- \note;
\end{tikzpicture}

If I uncomment any of the two commented lines, I get an error message that "Package pgf Error: No shape named 3 is known."

How are the nodes 0, 1, 2 different from the nodes 3, 4, 5? Why can't I draw with the latter?

Answer 1

When you make the list with e.g. 3 / 2 / 1, the space is actually included, and it becomes included in the node name as well. Hence, if you were to do \draw (3 ) -- (4 );, note (X<space>), it works. Probably better to define the list without the spaces in the first place, i.e. 3/2/1.

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}
\foreach \k in {0,1,2} 
\node (\k) at (\k,\k*\k-2*\k) {\k};
\def\Data{
  3/2/1,
  4/1/2,
  5/2/3}
\foreach \a/\x/\y in \Data 
\node (\a) at (\x,\y) {\a};

\draw (0) -- (2);
\draw (3) -- (4);
\foreach \note  [remember=\note as \lastnote (initially {(0)})] in {(1),(2)} \draw[->] \lastnote -- \note;
\foreach \note  [remember=\note as \lastnote (initially {(3)})] in {(4),(5)} \draw[->] \lastnote -- \note;
\end{tikzpicture}

\end{document}