Tikz – Block Diagrams with Matrices and Chains

chainmatrices

I'm trying to draw block diagrams with tikz.
For that I'd like to use matrices to align the nodes and then connect the nodes with the tikzlibrary chains, as described in the pgfmanual page 601 (chapter 48).

However, within some blocks I'd like to place custom pictograms. Once I do that, I cannot chain blocks containing custom pictograms together.

I've got the idea from this texample, which I cannot get to compile either.

Consider the following MWE:

\usetikzlibrary{chains, scopes, matrix}

\begin{tikzpicture}

% I'd like to have a block with two circles within
\def\circles{
    \node{};
    \draw (-1mm,0) circle(2mm) (2mm,0) circle(2mm);
}

\matrix (m) [matrix of nodes, 
    nodes={draw,
        minimum size=1cm,
        align=center,
        anchor=center},
    column sep=1cm,
    row sep=1cm,
]
{
    A & B & C & \circles \\
};

{ [start chain, every on chain/.style={join=by ->}]
    \chainin (m-1-1);
    \chainin (m-1-2);
    \chainin (m-1-3);
%   \chainin (m-1-4); % once uncommented, it doesn't compile
};

\end{tikzpicture}

With the code as is I get the following result:

Once I uncomment the last \chainin (m-1-4); statement though, I get the error message

[LaTeX] Line 87: Package pgf Error: No shape named `chain-1' is known.
[LaTeX] Line 87: See the pgf package documentation for explanation. ...                                                                                                
l.80    \chainin (m-1-4);

Any idea how I could connect a node with such a pictogram within a chaining sequence?

Best Answer

If understood you correctly than you are after the following:

MWE, which produce above images, use only arrows.meta, chains and positioning libraries. Arrows between nodes are drawn by macro join defined in chains library.,

\documentclass[border=3.141592]{standalone}
\usepackage{tikz}
\usetikzlibrary{chains, 
                positioning}
\newcommand\dcircle{\tikz{\draw (-0.1,0) circle[radius=2mm] (0.1,0) circle[radius=2mm]}}

\begin{document}
    \begin{tikzpicture}[
node distance = 1cm and 1cm,
  start chain = going right,
     N/.style = {draw, minimum size=1cm, semithick,
                 on chain, join=by ->}
                        ]
\foreach \i [count=\x] in {A, B , C, \dcircle}
\node [N] {\i};
    \end{tikzpicture}
\end{document}

Related Solutions

[Tex/LaTex] How to typeset block matrices

I think you want to look into the easybmat package.

Here's an example.

\[
\left(
\begin{BMAT}(rc){c:c}{c:c}
0 & \begin{BMAT}(rc){ccc}{ccc}
        1 & &\\
        & 2 &\\
        & & 3
    \end{BMAT}\\
\begin{BMAT}(rc){ccc}{ccc}
4 & &\\
& 5 &\\
& & 6
\end{BMAT} & 0
\end{BMAT}
\right)
\]

[Tex/LaTex] How to label arrows in tikz-cd diagrams with matrices

This is because the tikz-cd environment is a wrapper around a TikZ matrix and in a TikZ matrix then & doesn't mean what it usually means. Inside a TikZ matrix then & is a command which does a fair bit extra than the usual "hop to the next cell". However, inside an AMS matrix, you want it to be just the "hop to the next cell" that it usually is. So the two occurrences of & in your code have different meanings but you are using the same symbol for them. There are a variety of ways to fix this:

Keep the normal meaning of & so that it works inside the AMS matrix, in which case you need to use something else for the TikZ matrix. Fortunately, TikZ provides a way to do this: you write [ampersand replacement=\&] (or whatever) after the \begin{tikzcd} and then use \& (or whatever) for the TikZ cell separator.
Keep TikZ's meaning of & so that it works for the TikZ matrix, in which case you need to use something else for the AMS matrix. This is also quite straightforward. You put \let\amsamp=& in your preamble and then use \amsamp in your code (unfortunately, it would appear that \& can't be used here).
Rejig AMS's matrix environment to reset & to its usual meaning whilst inside its environs. This isn't quite as easy as it looks due to the fact that when the environment is read then the catcode of & is already frozen (as it is in the argument to a macro, in this case \arrow). So we have to do a bit of \begingroup ... \endgroup trickery when defining the new type of matrix environment. (Obviously, to do this right one should just redefine the basic AMS matrix environment that all the others are built on top of). Note that this also works outside tikzcd environments because what it actually does is say "If & is a command, let it be what & usually is." (okay, it's slightly more complicated but that'll do for now) and in the normal circumstances & isn't a command so this is (almost) a NO-OP.

\documentclass{article}
%\url{http://tex.stackexchange.com/q/81618/86}
\let\amsamp=&

\usepackage{amsmath}
\usepackage{tikz-cd}

\begingroup
\catcode`\&=13
\gdef\pampmatrix{%
  \begingroup
  \let&=\amsamp
  \begin{pmatrix}%
}
\gdef\endpampmatrix{\end{pmatrix}\endgroup}
\endgroup

\begin{document}

\[
\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}
\]

\begin{tikzcd}[ampersand replacement=\&]
A \arrow{r}{ \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix} } \& B
\end{tikzcd}

\begin{tikzcd}
A \arrow{r}{ \begin{pmatrix} 1 \amsamp 0 \\ 0 \amsamp 1 \end{pmatrix}
} & B
\end{tikzcd}

\begin{tikzcd}
A \arrow{r}{ \begin{pampmatrix}
 1 & 0 \\ 0 & 1 \end{pampmatrix} } & B
\end{tikzcd}

\[
  \begin{pampmatrix}
  1 & 0 \\ 0 & 1
  \end{pampmatrix}
\]
\end{document}

ampersands and matrices with TikZ and AMS

As a postscript (or PDF), I would like to point out that this is a lovely example of the distinction between fudge, Finagle, and diddle factors as explained in an article in THE IRE STUDENT QUARTERLY, SEPTEMBER 1958 (also reproduced in the wonderful book A Random Walk in Science, or it might be in More Random Walks in Science). The following is the relevant part:

However, John W. Campbell feels there is a different basic structure behind the Finagle, fudge and diddle factors. The Finagle factor, he claims, is characterized by changing the universe to fit an equation. The fudge factor, on the other hand, changes the equation to fit the universe. And finally, the diddle factor changes things so that the universe and the equation appear to fit, without making any real change in either.

For example, the planet Uranus was introduced to the universe when Newtonian laws couldn't be to match known planetary motions. This is a beautiful example of the application of the Finagle factor.

Einstein's work leading to relativity was strongly influenced by the observed facts about the orbit of Mercury. Obviously a fudge factor was introduced.

The photographer's use of a "soft-focus" lens when taking portraits of women over 35 is an example of the diddle factor. By blurring the results, photographs are made to appear to match the facts in a far more satisfactory manner.

Thus the first solution, which changes TikZ to fit AMS, is clearly an application of the Finagle factor. The second, which changes AMS to fit TikZ, is obviously a fudge. The last, in which everything suddenly appears to work with no outward change, is a definite diddle.

Best Answer

Related Solutions

[Tex/LaTex] How to typeset block matrices

[Tex/LaTex] How to label arrows in tikz-cd diagrams with matrices

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