Krdytkyu

I am using tikz to reproduce a Matlab picturization of a neural network. The original figure that I need to reproduce is this :

I am stuck at plotting the tanh function and the linear function inside the node.
I have tried two methods as of now : pgfplots and tikz plot function but I am unable to move the plot inside the rectangle.

documentclass[class=minimal,border=0pt]{standalone}

usepackage{ifthen}

usepackage{pgf,tikz}

usepackage{pgfplots}

pgfplotsset{compat=1.15}

usepackage{tikz-3dplot}

usepackage{mathrsfs}

usetikzlibrary{arrows}

usepackage{tkz-euclide}

usetkzobj{all}

pagestyle{empty}



begin{document}



definecolor{bg_deepred}{RGB}{150,0,24}



begin{tikzpicture}

    [grid/.style={very thin,gray},

    conn/.style={->,blue,very thick},

    inp/.style={opacity=.5,very thick,black,fill=red},

    oup/.style={opacity=.5,very thick,black,fill=blue},

    int/.style={opacity=.5,very thick,black,fill=gray},

    int1/.style={opacity=.5, thick, black, fill=yellow},

    plane/.style={opacity=.6,draw=none,fill=yellow!80!black},

    line/.style={very thick}]



    % input layer

    draw[inp,rounded corners] (-1, 2.5) rectangle (1, -3.8) {};



    % scalar values (only internal circles)

    shade[ball color=green] (0,.5) circle (.5cm);

    draw (0,0.5) node[scale=2]{2};

    shade[ball color=green] (0,1.7) circle (.5cm);

    draw (0,1.7) node[scale=2]{1};



    draw (0,-0.4) node[circle,fill,inner sep=1pt](a){};

    draw (0,-0.7) node[circle,fill,inner sep=1pt](b){};

    draw (0,-1.0) node[circle,fill,inner sep=1pt](c){};





    shade[ball color=green] (0,-1.8) circle (.5cm);

    draw (0,-1.8) node[scale=2]{26};

    shade[ball color=green] (0,-3) circle (.5cm);

    draw (0,-3) node[scale=2]{27};

    %draw [fill=bg_deepred](0,y) circle (2.5mm);



    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    % input layer

    draw[int,rounded corners] (3, 2) rectangle (8, -3) {};



    draw[int1] (3.5, 1.5) rectangle (5, 0) {};

    draw[int1] (3.5, -1) rectangle (5, -2.5) {};



    draw[int1] (6.0, 1.5) rectangle (7.5, -2.5) {};



    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    % output layer

    draw[int,rounded corners] (10, 2) rectangle (15, -3) {};



    draw[int1] (10.5, 1.5) rectangle (12, 0) {};

    draw[int1] (10.5, -1) rectangle (12, -2.5) {};

    draw[int1] (13.0, 1.5) rectangle (14.5, -2.5) {};



    %tikz version not working

    begin{scope}[x=1pt,y=10pt,shift={(100,0)}]

      draw (5,5) plot[domain=-8:8] (x,{1/(1 + exp(-x))-0.5});

    end{scope}



    %pgfplots version not working

    begin{axis}[width=5.5cm,height=4cm,ymin=-1.25,ymax=1.25,xmin=-5,xmax=5]

    addplot[blue,smooth] {tanh(x)};

    end{axis}





end{tikzpicture}



end{document}

This gives me the followin with the blue curve provided using pgfplots package and the black one provided by the tikzplot package.

Like this?

You have to adjust the shift of scope so that its placed at the middle of node. Then just scale to required value.

MWE

documentclass[class=minimal,border=2mm]{standalone}

usepackage{tikz}    

begin{document}    

begin{tikzpicture}

    [grid/.style={very thin,gray},

    conn/.style={->,blue,very thick},

    inp/.style={opacity=.5,very thick,black,fill=red},

    oup/.style={opacity=.5,very thick,black,fill=blue},

    int/.style={opacity=.5,very thick,black,fill=gray},

    int1/.style={opacity=.5, thick, black, fill=yellow},

    plane/.style={opacity=.6,draw=none,fill=yellow!80!black},

    line/.style={very thick}]



    % input layer

    draw[inp,rounded corners] (-1, 2.5) rectangle (1, -3.8) {};



    % scalar values (only internal circles)

    shade[ball color=green] (0,.5) circle (.5cm);

    draw (0,0.5) node[scale=2]{2};

    shade[ball color=green] (0,1.7) circle (.5cm);

    draw (0,1.7) node[scale=2]{1};



    draw (0,-0.4) node[circle,fill,inner sep=1pt](a){};

    draw (0,-0.7) node[circle,fill,inner sep=1pt](b){};

    draw (0,-1.0) node[circle,fill,inner sep=1pt](c){};



    shade[ball color=green] (0,-1.8) circle (.5cm);

    draw (0,-1.8) node[scale=2]{26};

    shade[ball color=green] (0,-3) circle (.5cm);

    draw (0,-3) node[scale=2]{27};

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    % input layer

    draw[int,rounded corners] (3, 2) rectangle (8, -3) {};

    draw[int1] (3.5, 1.5) rectangle (5, 0) {};

    draw[int1] (3.5, -1) rectangle (5, -2.5) {};

    draw[int1] (6.0, 1.5) rectangle (7.5, -2.5) {};

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    % output layer

    draw[int,rounded corners] (10, 2) rectangle (15, -3) {};  

    draw[int1] (10.5, 1.5) rectangle (12, 0) {};

    draw[int1] (10.5, -1) rectangle (12, -2.5) {};

    draw[int1] (13.0, 1.5) rectangle (14.5, -2.5) {};



    %tikz version working

    begin{scope}[x=2pt,y=2cm,shift={(6.75cm,-0.5cm)}]

      draw[gray!50,thick] (-8,0) -- (8,0);

      draw[gray!50,thick] (0,-1cm) -- (0,1cm);

      draw[thick] (0,0) plot[domain=-8:8] (x,{1/(1 + exp(-x))-0.5});

    end{scope}



    %tikz version working

    begin{scope}[x=2pt,y=2cm,shift={(13.75cm,-0.5cm)}]

      draw[gray!50,thick] (-8,0) -- (8,0);

      draw[gray!50,thick] (0,-1cm) -- (0,1cm);

      draw[thick] (-8,-1cm)--(8,1cm);

    end{scope}    

end{tikzpicture} 

end{document}

an alternative approach:

• use of small pictures pic for nodes symbols


• symbols are not needed to be drawn with plot function, it is sufficient to approximate it with controls macro


• used are relative coordinates


• 
  

  shown are only hidden and output node

  
  
  

  documentclass[tikz,margin=3.141529mm]{standalone}
  
  usetikzlibrary{arrows.meta, backgrounds, calc, fit, positioning}
  
  
  
  begin{document}
  
      begin{tikzpicture}[
  
      node distance = 4mm and 4mm,
  
      arr/.style = {semithick, -{Triangle[width=3pt,length=3pt]}, rounded corners},
  
      box/.style = {draw, semithick, fill=yellow!40,
  
                    minimum size=6mm, inner sep=1mm, outer sep=0mm},
  
     circ/.style = {circle, draw,fill=white, inner sep=0.5mm, outer sep=0mm,
  
                    node contents={}},
  
      FIT/.style = {draw, fill=blue!20, rounded corners, inner sep=2mm, outer sep=0mm,
  
                    fit=#1, node contents={}},
  
      sum/.style = {circle, draw, fill=yellow!40, inner sep=0mm, outer sep=0mm,
  
                    font=large, node contents={+}},
  
        lin/.pic = {draw[very thin]  (-0.4,0) -- ++ (0.8,0)
  
                                      (0,-0.5) -- ++ (0,1.0);
  
                    draw[semithick]  (-0.4,-0.4) -- (0.4,0.4);
  
                      },
  
        sat/.pic = {draw[very thin]  (-0.4,0) -- ++ (0.8,0)
  
                                      (0,-0.5) -- ++ (0,1.0);
  
                    draw[semithick]
  
                      (-0.4,-0.4) .. controls + (2mm,0mm) and + (-2mm,-4mm) .. (0,0)
  
                                  .. controls + (2mm,4mm) and + (-2mm, 0mm) .. (0.4,0.4);
  
                      },
  
                          ]
  
  % hidden node
  
  node (a1)  [box] {$W$};
  
  node (a2)  [box, below=of a1]  {b};
  
  node (a3)  [sum, right=of $(a1.east)!0.5!(a2.east)$];
  
  path   let p1 = ($(a1.north)-(a2.south)$),
  
              n1 = {veclen(x1,y1)} in
  
          node (a4) [box, minimum height=n1,
  
                     right=of a3] {};
  
  pic[scale=0.5] at (a4.center) {sat};
  
      draw[arr] (a1) -| (a3);
  
      draw[arr] (a3) edge (a4) (a2) -| (a3);
  
  scoped[on background layer]
  
      node (a5)  [FIT=(a1) (a4)];
  
  node (a6) [circ,at=(a5.west |- a1)];
  
  draw[arr] (a6) -- (a1);
  
  % output node
  
      begin{scope}[xshift=33mm]
  
  node (b1)  [box] {$W$};
  
  node (b2)  [box, below = of b1]  {b};
  
  node (b3)  [sum, right=of $(b1.east)!0.5!(b2.east)$];
  
  path   let p1 = ($(b1.north)-(b2.south)$),
  
              n1 = {veclen(x1,y1)} in
  
          node (b4) [box, minimum height=n1,
  
                     right=of b3] {};
  
  pic[scale=0.5] at (b4.center) {lin};
  
      draw[arr] (b1) -| (b3);
  
      draw[arr] (b3) edge (b4) (b2) -| (b3);
  
  scoped[on background layer]
  
      node (b5)  [FIT=(b1) (b4)];
  
  node (b6) [circ,at=(b5.west |- a1)];
  
  draw[arr] (b6) -- (b1);
  
      end{scope}
  
      end{tikzpicture}
  
  end{document}