How to add an equal sign between two nodes in tikzpicture

Question

How can I add an equals sign between the leftmost "A" and the next "A" to the right?

Here's what I have so far:

\usepackage{graphicx}
\usetikzlibrary{arrows,shapes,decorations,automata,backgrounds,petri,positioning}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{width=7cm,compat=1.3}
\tikzstyle{arrow} = [draw, -latex']
\tikzstyle{node} = [rectangle, draw, text centered]
\begin{document}
\begin{figure}[ht]
        \centering
        \begin{tikzpicture}[node distance=1.4cm]
        \tikzstyle{place}=[circle,thick,draw=gray!75,fill=gray!20,minimum size=6mm] 
        \node (ae) [node] {A};
        \node (a0) [node, right=1.5cm of ae] {A};
        \node (a1) [node, right of=a0] {A};
        \node (a2) [node, right of=a1] {A};
        \node (a3) [node, right of=a2] {A};
        \node (x0) [node, below of=ae] {$X_t$};
        \node (x1) [node, below of=a0] {$X_0$};
        \node (x2) [node, below of=a1] {$X_1$};
        \node (x3) [node, below of=a2] {$X_2$};
        \node (x4) [node, below of=a3] {$X_t$};
        \node (h0) [node, above of=ae] {$h_t$};
        \node (h1) [node, above of=a0] {$h_0$};
        \node (h2) [node, above of=a1] {$h_1$};
        \node (h3) [node, above of=a2] {$h_2$};
        \node (h4) [node, above of=a3] {$h_t$};
    \draw [red,-&gt;] (ae.45) arc (0:240:4mm) node[pos=0.5,above left]{}(ae);
    %\draw [=] (ae) -- (a0)
    \draw [arrow] (a0) -- (a1);
    \draw [arrow] (a1) -- (a2);
    \draw [arrow] (a2) -- (a3);
    \draw [arrow] (x0) -- (ae);
    \draw [arrow] (x1) -- (a0);
    \draw [arrow] (x2) -- (a1);
    \draw [arrow] (x3) -- (a2);
    \draw [arrow] (x4) -- (a3);
    \draw [arrow] (ae) -- (h0);
    \draw [arrow] (a0) -- (h1);
    \draw [arrow] (a1) -- (h2);
    \draw [arrow] (a2) -- (h3);
    \draw [arrow] (a3) -- (h4);

    \end{tikzpicture}

\end{figure}
\end{document}

Alternatively use How to center one node exactly between two others with TikZ? - TeX - LaTeX Stack Exchange for accuracy — user202729, May 16 '22 at 03:09
Note: You need to load tikz before any of the libraries. You have it reversed in your code. Also, the \documentclass is missing. — Sandy G, May 16 '22 at 03:18

Black Mild · Answer 1 · 2022-05-16T18:40:50.573

7

The following gives a simpler code. No more library is needed; handy \foreach with 2 variables; \a and \b for controlling the vertical and horizontal distances.

\documentclass[tikz,border=5mm]{standalone}
\begin{document}
\begin{tikzpicture}[>=latex]
\def\a{2} \def\b{2.2}
\foreach \i/\j in {-1/t,0/0,1/1,2/2,3/t}{
\path[nodes={draw}]
(\i*\b,0) node (a\i) {$A$}
+(0,\a)   node (h\i) {$h_{\j}$}
+(0,-\a)  node (x\i) {$X_{\j}$}
;
\draw[->] (a\i)--(h\i);
\draw[->] (x\i)--(a\i);
}
\draw[->] (a0)--(a1);
\draw[->] (a1)--(a2);
\draw[->] (a2)--(a3);
\draw[->,magenta] (a-1.north east) arc (0:240:.4); 
\path (a-1)--(a0) node[midway,blue]{=};
\end{tikzpicture}
\end{document}

edited May 16 '22 at 18:40

answered May 16 '22 at 05:56

Black Mild

17,569

2

Very nice solution!+1 – Zarko May 16 '22 at 06:33
Thanks! most people does not pay attention to the simplicity of code, and figures itself – Black Mild May 16 '22 at 07:16
Try \newcommand\a{2} :) An alternative is declare function={a=2;b=2.2;} in the options to the tikzpicture, and use a/b instead of \a/\b in the coordinates in the loop. – Torbjørn T. May 16 '22 at 18:54

score 6 · Answer 2 · answered May 16 '22 at 03:17

The usage of the positioning library is right=of ae not right of=ae. So you should change all your nodes. Then you can add \node [right=.7cm of ae.center]{=}; for your = sign, since your node distance is set to 1.4cm.

    \node (ae) [node] {A};
    \node (a0) [node, right=of ae] {A};
    \node (a1) [node, right=of a0] {A};
    \node (a2) [node, right=of a1] {A};
    \node (a3) [node, right=of a2] {A};
    \node (x0) [node, below=of ae] {$X_t$};
    \node (x1) [node, below=of a0] {$X_0$};
    \node (x2) [node, below=of a1] {$X_1$};
    \node (x3) [node, below=of a2] {$X_2$};
    \node (x4) [node, below=of a3] {$X_t$};
    \node (h0) [node, above=of ae] {$h_t$};
    \node (h1) [node, above=of a0] {$h_0$};
    \node (h2) [node, above=of a1] {$h_1$};
    \node (h3) [node, above=of a2] {$h_2$};
    \node (h4) [node, above=of a3] {$h_t$};
    \node [right=.7cm of ae.center]{=};

Zarko · Answer 3 · 2022-05-16T10:49:08.907

Try the following MWE:

\documentclass{article}
\usepackage{graphicx}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18,
             width=7cm}
\usetikzlibrary{arrows.meta, automata,
                backgrounds,
                chains,
                decorations,
                petri, positioning,
                shapes}
\begin{document}
    \begin{figure}[ht]
    \centering
    \begin{tikzpicture}[
            > = Straight Barb,
node distance = 12mm and 12mm,
  start chain = going right,
     N/.style = {draw, minimum size=2em}
                        ]
\foreach \i [count=\x]  in {t,0,1,2,t,5}
{
\ifnum\x=2
    \node (a\x) [N,on chain] {$A$};
\else
    \node (a\x) [N,on chain, join=by ->] {$A$};
\fi
\node (x\x) [N, below =of a\x] {$X_{\i}$};
\node (h\x) [N, above =of a\x] {$h_{\i}$};
\draw[->]   (x\x) -- (a\x);
\draw[->]   (a\x) -- (h\x);
}
\path(a1) -- node {$=$} (a2);  %  <---
\draw[red,->] (a1.45) arc (0:240:1.414em);
    \end{tikzpicture}
    \end{figure}
\end{document}

In it is used

for pgfplots, which also load tikz package I suggest to use recent version 1.18 which introduce many new functionalities and fix may bugs from the "ancient" version onwards (it is time to upgrade your LaTeX installation).
recent tikz syntax for defining styles of image elements (\tikzstyle is deprecated for long time ago)
rows with nodes A are positioned by use of chains library and connected with exception the first two by macro join = by ->
first two, what was your problem, are connected by path with node with = in the middle.

Result of MWE compilations is:

How to add an equal sign between two nodes in tikzpicture

3 Answers3