An optimized set of tikz code?

Question

I have a question, how can have the shortest set of tikz code for this picture?

I am tring to optimize this code:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\begin{document}
La version de TikZ est : \pgfversion

    \vfill  

\begin{center}
    \begin{tikzpicture}
    %
        \draw (0,1) -- (1,0);
    \draw (1,0) -- (0,-1);
    \draw (0,-1) -- (-1,0);
    \draw (-1,0) -- (0,1);
    \draw (0,0) circle (1);
    \draw (0,1) circle (1);
    \draw (0,-1) circle (1);
    \draw (-1,0) circle (1);
    \draw (1,0) circle (1);
    %
        \draw (0,2) -- (2,0);
        \draw (2,0) -- (0,-2);
        \draw (0,-2) -- (-2,0);
        \draw (-2,0) -- (0,2);
        \draw (0,0) circle (2);
        \draw (0,2) circle (2);
        \draw (0,-2) circle (2);
        \draw (-2,0) circle (2);
        \draw (2,0) circle (2);
    \end{tikzpicture}   
\end{center}
\end{document}

Answer 1

One path for everything. EDIT: Because AndréC accused me of copying from "his" answer, this the original answer:

\documentclass[tikz,border=3.14mm]{standalone}
\begin{document}
\begin{tikzpicture}
  \draw[rotate=45]  foreach \Y in {1,2} 
   {(0,0) circle[radius=\Y]
    ({-\Y/sqrt(2)},{-\Y/sqrt(2)}) rectangle ({\Y/sqrt(2)},{\Y/sqrt(2)})
   foreach \X in {45,135,225,315}
   { (\X:\Y) circle[radius=\Y]}};
\end{tikzpicture}
\end{document}

To put things into perspective:

1. Paul Gaborit's answer is also one path. I should have mentioned this above.
2. Paul Gaborit had the first answer here, which I upvoted, and which uses polar coordinates.
3. As one can see, I used polar coordinates right from the start.
4. The new features of this answer are two nested foreach loops and drawing the rotated rectangles as rotated rectangles.
5. On the other hand AndréC's answer copies the two loops from mine. (I became only aware of "his" answer long after the following code was written.)

\documentclass[tikz,border=3.14mm]{standalone}
\begin{document}
\begin{tikzpicture}
  \draw[rotate=45]  foreach \Y in {1,2} 
   {(0,0) circle[radius=\Y]
    (45:\Y) rectangle (225:\Y)
   foreach \X in {45,135,225,315}
   { (\X:\Y) circle[radius=\Y]}};
\end{tikzpicture}
\end{document}

Answer 2

Here is a solution (not the shortest):

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
  \draw
  circle (1) circle(2)
  (0:1) --(90:1) -- (180:1) -- (270:1) -- cycle
  (0:1) circle(1) (90:1) circle(1) (180:1) circle(1) (270:1) circle(1)
  (0:2) --(90:2) -- (180:2) -- (270:2) -- cycle
  (0:2) circle(2) (90:2) circle(2) (180:2) circle(2) (270:2) circle(2);
\end{tikzpicture}
\end{document}

Answer 3

Just for fun:

\documentclass[tikz,margin=5mm]{standalone}
\begin{document}
\begin{tikzpicture}

\draw (0,0) circle (1) circle (2);

\foreach \t/\n in {0/1,90/2,180/3,270/4}{
  \draw (\t:1)coordinate(\n) circle (1)  ;}

\foreach \t/\m in {0/5,90/6,180/7,270/8}{
  \draw (\t:2)coordinate(\m) circle (2) ;}

\draw (1)--(2)--(3)--(4)--cycle;
\draw (5)--(6)--(7)--(8)--cycle;  


\end{tikzpicture}
\end{document}

Answer 4

Borrowing a bit from everyone:

\documentclass[tikz,border=5]{standalone}
\begin{document}
\tikz\draw\foreach~in{1,2}{[rotate=45,scale=~/sqrt 2](-1,-1)rectangle(1,1)
  \foreach~in{0,...,4}{(~*90-45:{(~>0)*sqrt 2})circle(sqrt 2)}};
\end{document}

Answer 5

Not as much as @marmot's nicely optimised answer but a try (gives more knobs for fun though):

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}[mystyle/.style={circle,draw,fill=none,minimum size=20, line width = 0.1pt}]
\foreach \x/\y/\z in {0/0/2,0/1/2,0/-1/2,-1/0/2,1/0/2,0/0/4,0/1/4,0/-1/4,-1/0/4,1/0/4}
\node [mystyle,  minimum size = \z cm, color =black]  (2) at (\x, \y) {};
\foreach \x/\y in {-0.7/0.7, -1.41/1.41}
\draw[rotate=45, line width = 0.1pt] (\x , \x ) rectangle (\y, \y);
\end{tikzpicture}
\end{document}

which gives

Answer 6

I am participating in the celebration with two proposals, both of which have been made:

Two loops:

• the first one to make an enlargement (scale) by two
• the second to build the 4 circles and the square using polar coordinates

The code is indented so that it can be read:

First proposal (easier to read):

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\begin{document}
La version de TikZ est : \pgfversion

    \vfill  

\begin{center}
\begin{tikzpicture}
\foreach  \s in {1,2}{
        \begin{scope}[scale=\s]
            \draw (0,0) circle (1);
            \foreach \r [remember= \r as \rr (initially 270)] in {0,90,180,270}{
                \draw (\r:1) circle (1);
                \draw (\rr:1)--(\r:1);
                }
        \end{scope}
        }
\end{tikzpicture}   
\end{center}
\end{document}

Second proposal (without scope environment):

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\begin{document}
La version de TikZ est : \pgfversion

    \vfill  

\begin{center}
\begin{tikzpicture}
\foreach  \s in {1,2}{
            \draw (0,0) circle (\s);
            \foreach \r [remember= \r as \rr (initially 270)] in {0,90,180,270}{
                \draw (\r:\s) circle (\s);
                \draw (\rr:\s)--(\r:\s);
                }
        }
\end{tikzpicture}   
\end{center}
\end{document}