Arrow head erroneously shows on both sides

Question

I'm creating a simple depiction of a Queue data structure, the code is very simple with just a matrix of math nodes and two extra nodes (one being enqueued and the other dequeued). When adding an edge from enqueued node to the queue representation, I get an arrow head on both ends, instead of only one. How can I solve this?

Here's an image of the problem:

problem

And here's a minimal example to reproduce the issue:

\documentclass[crop]{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}
\usetikzlibrary{positioning}
\tikzstyle{box} = [rectangle, draw, text centered,
  minimum height=1cm, minimum width=1cm]
\begin{document}
\begin{tikzpicture}
  \matrix (q) [matrix of math nodes, nodes={box, thick}]
          {
            0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \
          };
  \node[box, thick, left=25pt of q, rotate=15] (enq) {};
  \node[box, thick, right=25pt of q, rotate=-15] (deq) {};
\draw[->, thick]
  (enq.east) edge [bend left] node [pos=0.5, above, sloped] { \tiny Enqueue } (q-1-1.west);
\draw[->, thick]
  (q-1-8.east) edge [bend left] node [pos=0.5, above, sloped] { \tiny Dequeue} (deq.west);
\end{tikzpicture}
\end{document}

PS: if I remove the explicit anchors from the edge definition, the extra arrow heads are removed, but the edge is placed a little too high.

Hi, welcome. Use to instead of edge. See for example https://tex.stackexchange.com/questions/169564/ https://tex.stackexchange.com/questions/15567/ https://tex.stackexchange.com/questions/82326/ — Torbjørn T., Nov 27 '22 at 15:15
Thank you, @TorbjørnT. The solution was much simpler than I thought :-) — Felipe Balbi, Nov 27 '22 at 15:20

score 1 · Accepted Answer · answered Nov 27 '22 at 16:05

You can define edge style, for example as every edge/.style = {draw, -stealth}, as well edge labels as every edge/.style = {draw, -stealth},˛. Considering this definitions and colors of nodes shows in image, the MWE can be:

\documentclass[crop]{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix,
                positioning,
                quotes}
\begin{document}
\begin{tikzpicture}[
box/.style = {draw=#1, thick, fill=#1!30,
              minimum size=1cm, align=center},
every edge/.style = {draw, -stealth},
every edge quotes/.style = {auto, font=\tiny}
                    ]
\matrix (q) [matrix of math nodes,
             nodes = {box=orange, outer sep=0pt},
             column sep = -\pgflinewidth,
             inner sep=0pt]
{
0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \
};
\node[box=red,   left =12mm of q, rotate= 15] (enq) {};
\node[box=green, right=12mm of q, rotate=-15] (deq) {};
\draw   (enq.east)  edge[bend left, sloped, "Enqueue"] (q.west);
\draw   (q.east)    edge[bend left, sloped, "Dequeue"] (deq.west);
\end{tikzpicture}
\end{document}

Arrow head erroneously shows on both sides

1 Answers1