Center environment doesn't center a TikZ figure

Question

It seems to be lots of problems like this in the archive but none seems to match mine.

I have a TikZ figure that depends on \draw. I know that keys off an assumed Cartesian plane and maybe that is the problem with centering -- if so I might be screwed.

Anyway, here is the code:

\documentclass{amsbook}
\usepackage{tikz}
\begin{document}
\def\SetA{(0,0) circle (1.5cm)}
\def\SetB{(1,2) circle (1.5cm)}
\def\SetC{(2,0) circle (1.5cm)}
\begin{center}
\begin{figure}
\begin{tikzpicture}
        \draw (-3,-2) rectangle (5,4);
        \draw (4.5,3.5) node {$\mathcal{U}$};
        \draw (-2,2) node {$A \cap B$};
        \draw (4,2) node {$A \cap C$};
    \draw \SetA node[below] {$A$};
    \draw \SetB node [above] {$B$};
    \draw \SetC node [below] {$C$};
\begin{scope}
  \clip \SetA;  
  \fill[red] \SetB;  
\end{scope}

\begin{scope}
  \clip \SetA;
  \clip \SetB;
  \fill[green] \SetC;
\end{scope}

\end{tikzpicture}
\caption{Examples of Intersection}
\end{figure}
\end{center}
\end{document}

And here is the output:

Since I haven't figured out how to add a graphic I'll describe it: the TikZ figure is a little to the left and the caption appears to be centered. Of course. I'd like them both to be centered. (Maybe some kind person could explain what I should do After I click image to add same.) — TonyK, Dec 14 '21 at 06:50
For adding the image, see here: https://tex.meta.stackexchange.com/questions/2136/how-can-i-upload-an-image-to-be-included-in-a-question-or-answer?rq=1 — CarLaTeX, Dec 14 '21 at 07:24

CarLaTeX · Accepted Answer · 2021-12-14T07:03:09.037

Don't use figure environment within a center evironment, just use figure with \centering.

See When should we use \begin{center} instead of \centering?.

I also added caption package for a better caption alignment.

\documentclass{amsbook}
\usepackage{caption}
\usepackage{tikz}
\begin{document}
\def\SetA{(0,0) circle (1.5cm)}
\def\SetB{(1,2) circle (1.5cm)}
\def\SetC{(2,0) circle (1.5cm)}
\begin{figure}\centering
\begin{tikzpicture}
        \draw (-3,-2) rectangle (5,4);
        \draw (4.5,3.5) node {$\mathcal{U}$};
        \draw (-2,2) node {$A \cap B$};
        \draw (4,2) node {$A \cap C$};
    \draw \SetA node[below] {$A$};
    \draw \SetB node [above] {$B$};
    \draw \SetC node [below] {$C$};
    \begin{scope}
      \clip \SetA;  
      \fill[red] \SetB;  
    \end{scope}
    \begin{scope}
      \clip \SetA;
      \clip \SetB;
      \fill[green] \SetC;
    \end{scope}
\end{tikzpicture}
\caption{Examples of Intersection}
\end{figure}
\end{document}

Alternatively, you can use center without figure, in this case add the caption with \captionof:

\documentclass{amsbook}
\usepackage{caption}
\usepackage{tikz}
\begin{document}
\def\SetA{(0,0) circle (1.5cm)}
\def\SetB{(1,2) circle (1.5cm)}
\def\SetC{(2,0) circle (1.5cm)}
\begin{center}
\begin{tikzpicture}
        \draw (-3,-2) rectangle (5,4);
        \draw (4.5,3.5) node {$\mathcal{U}$};
        \draw (-2,2) node {$A \cap B$};
        \draw (4,2) node {$A \cap C$};
    \draw \SetA node[below] {$A$};
    \draw \SetB node [above] {$B$};
    \draw \SetC node [below] {$C$};
    \begin{scope}
      \clip \SetA;  
      \fill[red] \SetB;  
    \end{scope}
    \begin{scope}
      \clip \SetA;
      \clip \SetB;
      \fill[green] \SetC;
    \end{scope}
\end{tikzpicture}
\captionof{figure}{Examples of Intersection}
\end{center}
\end{document}

The difference between the two is that figure floats (that is, LaTeX put it where it's better), whereas center does not (it is placed where it is).

Two answers for the price of one. Awesome! Thank you CarlaTeX. So much I don't know. And just in case anyone thinks I created this TikZ figure -- nope. Piecing things together from code stolen from here. — TonyK, Dec 14 '21 at 07:14
@TonyK As an old Italian COBOL programmer I told you only Spoletini wrote, all the others copy-pasted (Spoletini wrote a COBOL manual in Italian) :D Thank you for accepting my answer. — CarLaTeX, Dec 14 '21 at 07:19

Center environment doesn't center a TikZ figure

1 Answers1