Sfrgttk

Could someone, whenever it's possible, post a minimal tikZ example to draw this? I also would like to put an "R" inside the upper box. This is mi code so far (I know, it's a mess):

documentclass[tikz]{standalone}

begin{document}

tikzstyle{vspecies}=[rectangle, minimum size=0.5cm,draw=black,fill=blue]

begin{tikzpicture}



node [vspecies] (I) {I} ;

node [vspecies, above left of = I] (N) {M} ;

node [vspecies, below left of = I] (K) {K} ;

draw [->,thick] (S.south east) --  node {small{$N$}}  (M) ; ;

draw [->,thick] (C) --  node [below right]    {small{$M$}} (M) ;



end{tikzpicture}

end{document}

Just for fun.

documentclass[tikz]{standalone}

usetikzlibrary{positioning}

begin{document}

tikzset{vspecies/.style={rectangle, minimum size=0.5cm,draw=blue}}

begin{tikzpicture}[>=latex]

 node[draw,minimum width=1cm,minimum height=2cm,

 label=left:$M$,label=above:$N$] (R){$R$};

 node [vspecies,below left=1cm and 0.2cm of R,minimum height=1.2cm,

 label=left:$M$,label=above:$K$] (R1) {} ;

 node [vspecies,below right=1cm and 0.2cm of R,minimum width=1.2cm,

 label=left:$K$,label=above:$N$] (R2) {} ;

 draw [->,thick,shorten >=1mm,shorten <=1mm] (R.south west) -- (R1.north east);

 draw [->,thick,shorten >=1mm,shorten <=1mm] (R.south east) -- (R2.north west);

end{tikzpicture}

end{document}

Something like this?

documentclass[tikz,margin=1mm]{standalone}

usetikzlibrary{positioning}

begin{document}

begin{tikzpicture}

begin{scope}[local bounding box=a]

    node[minimum width=2cm,minimum height=3cm,draw] (main-a) {};

    path (main-a.west) node[left] {$N$} (main-a.north) node[above] {$M$};

end{scope}

begin{scope}[local bounding box=b2]

    node[minimum width=2cm,minimum height=1cm,draw,below right=of main-a] (main-b2) {};

    path (main-b2.east) node[right] {$K$} (main-b2.north) node[above] {$M$};

end{scope}

begin{scope}[local bounding box=b1]

    node[minimum width=1cm,minimum height=3cm,draw,below left=of main-a] (main-b1) {};

    path (main-b1.west) node[left] {$N$} (main-b1.north) node[above] {$K$};

end{scope}

draw[-stealth] (main-a.south) -- (b1.north east);

draw[-stealth] (main-a.south) -- (b2.north west);

end{tikzpicture}

end{document}

Here is an overkill solution that defines a new pics "shape" (see section 18.2 of the 3.1.1 tikz manual),together with some custom pgfkeys for styling it. The end result is that you can produce:

using code:

documentclass[tikz, border=5mm]{standalone}

usetikzlibrary{positioning}



begin{document}

pgfkeys{/vspecies/.is family, /vspecies,

  colour/.initial  = black, % rectangle colour

  fill/.initial    = white, % default fill

  top label/.initial = M,   % label on right

  right label/.initial= N,  % label on left

  bottom label/.initial=,   % label on left

  left label/.initial=,     % label on left

  X/.initial       = 5mm,   % default width

  Y/.initial       = 5mm,   % default height

  shape/.initial   = rectangle % default shape

}



tikzset{

pics/vspecies/.style args={#1,#2}{% node name, pgfkeys key-value pairs

     code = {

      pgfkeys{/vspecies, #2}

      node[pgfkeysvalueof{/vspecies/shape},

            minimum size=pgfkeysvalueof{/vspecies/X},

            minimum height=pgfkeysvalueof{/vspecies/Y},

            draw=pgfkeysvalueof{/vspecies/colour},

            fill=pgfkeysvalueof{/vspecies/fill},

            label=east:pgfkeysvalueof{/vspecies/left label},

            label=north:pgfkeysvalueof{/vspecies/top label},

            label=south:pgfkeysvalueof{/vspecies/bottom label},

            label=west:pgfkeysvalueof{/vspecies/right label},

      ](#1) at (0,0){};

     }

  }

}



begin{tikzpicture}

  pic at (0,0) {vspecies={A,colour=red,Y=10mm}};

  pic[below left=10mm of A] {vspecies={B,top label=K,colour=blue,Y=20mm}};

  pic[below right=10mm of A] {vspecies={C,fill=blue!10,X=10mm,shape=circle,left label=N,right label=}};

  draw[->](A.south west)--(B.north east);

  draw[->](A.south east)--(C.north west);

end{tikzpicture}



end{document}

The vspecies pic command take two arguments: the first is the name of a (normal) tikz node label and the second argunment is a comma separated list of key-value pairs tha specify:

• the colour of the rectangle (default black)


• the fill colour (default white)


• the top label (default M)


• the left label (default "")


• the bottom label (default "")


• the left label (default N)


• the minimum X width


• the minimum Y height


• the shape (default rectangle)

As I said, this is overkill (and I was bored:)

Final version:

documentclass[tikz,margin=1mm]{standalone}

usetikzlibrary{positioning}

begin{document}

sffamily

begin{tikzpicture}

begin{scope}[local bounding box=a]

node[minimum width=2cm,line width=0.199mm,minimum   height=3cm,draw=black] (main-a) {R};

path (main-a.west) node[left] {N} (main-a.north) node[above] {M};

end{scope}

begin{scope}[local bounding box=b2]

node[minimum width=2cm,line width=0.199mm,minimum height=1cm,draw=blue,below right=of main-a] (main-b2) {};

path (main-b2.east) node[right] {K} (main-b2.north) node[above] {M};

end{scope}

begin{scope}[local bounding box=b1]

node[minimum width=1cm,line width=0.199mm,minimum height=3cm,draw=blue,below left=of main-a] (main-b1) {};

path (main-b1.west) node[left] {N} (main-b1.north) node[above] {K};

end{scope}

draw[-stealth] (main-a.south) -- (b1.north east);

draw[-stealth] (main-a.south) -- (b2.north west);

end{tikzpicture}

end{document}