Customizing the hidden layer (number of nodes, color, connection) with TikZ

Question

I am a new user of TikZ and seeking help with this. I am trying to draw an autoassoicative neural network as illustrated in the figure below in terms of number of units and label with each layer fully connected to the one after.

Im stuck . I couldn't figure how to specify each hidden layer seperately. It ends up over-writing the hidden layer specs and fully connecting to the last hidden layer while the others remain unconnected as shown below.

Here is the code:

    \documentclass[border=0.125cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}

\tikzset{%
   neuron missing/.style={
    draw=none, 
    scale=2,
    text height=0.333cm,
    execute at begin node=\color{black}$\vdots$
  },
}

\begin{tikzpicture}[x=1.5cm, y=1.5cm, >=stealth]

\newcommand\Nhidden{3}

% First three nodes in Input Layer
\foreach \m/\l [count=\y] in {1,2,3}
{
 \node [circle,fill=green!50,minimum size=1cm] (input-\m) at (0,2.5-\y) {};
}
% Last  node in Input Layer
\foreach \m/\l [count=\y] in {4}
{
 \node [circle,fill=green!50,minimum size=1cm ] (input-\m) at (0,-2.5) {};
}
% The missing nodes in Input Layer
 \node [neuron missing]  at (0,-1.5) {};

%%%%%%

% First  node in Hidden Layer#1 (Mapping)
\foreach \m [count=\y] in {1,2,3,4,5,6}
  \node [circle,fill=red!50,minimum size=1cm ] (hidden-\m) at (2,0.75) {};

% Last  node in Hidden Layer#1 (Mapping)
\foreach \m [count=\y] in {7}
  \node [circle,fill=red!50,minimum size=1cm ] (hidden-\m) at (2,-1.85) {};

 % The missing nodes in Hidden Layer#1 (Mapping)
 \node [neuron missing]  at (2,-0.3) {};

%%%%%%%

% First  node in Hidden Layer#2 (Bottleneck)
\foreach \m [count=\y] in {1}
  \node [circle,fill=blue!50,minimum size=1cm ] (hidden-\m) at (4,1.5-\y) {};

 % Last  node in Hidden Layer#2 (Bottleneck)
\foreach \m [count=\y] in {2}
  \node [circle,fill=blue!50,minimum size=1cm ] (hidden-\m) at (4,-0.5-\y) {};

% The missing  nodes in Hidden Layer#2 (Bottleneck)
 \node [neuron missing]  at (4,-0.4) {};

 %%%%%%%  
 % First  node in Hidden Layer#3 (De-Mapping)
\foreach \m [count=\y] in {1,2,3,4,5,6}
  \node [circle,fill=red!50,minimum size=1cm ] (hidden-\m) at (6,0.75) {};

% Last  node in Hidden Layer#3 (De-Mapping)
\foreach \m [count=\y] in {7}
  \node [circle,fill=red!50,minimum size=1cm ] (hidden-\m) at (6,-1.85) {};

 % The missing nodes in Hidden Layer#1 (De-Mapping)
 \node [neuron missing]  at (6,-0.3) {};

%%%%%%%

% First three nodes in Output Layer
\foreach \m/\l [count=\y] in {1,2,3}
{
 \node [circle,fill=green!50,minimum size=1cm] (output-\m) at (8,2.5-\y) {};
}
% Last  node in Output Layer
\foreach \m/\l [count=\y] in {4}
{
 \node [circle,fill=green!50,minimum size=1cm ] (output-\m) at (8,-2.5) {};
}
% The missing nodes in Output Layer
 \node [neuron missing]  at (8,-1.5) {};



 %%%%%%%%%%------------------------------------

\foreach \l [count=\i] in {1,2,3,n}
  \draw [<-] (input-\i) -- ++(-1,0)
    node [above, midway] {$X_{\l}$};

\foreach \N in {1,...,\Nhidden} {
\foreach \l [count=\i] in {1,2,3,4,5,6,k}
  \node [above] at (hidden-\i.north) {$H_{m\l}$};

\foreach \l [count=\i] in {1,f}
  \draw [->] (hidden-\i) -- ++(1,0)
    node [above, midway] {$T_{ \l}$};


\foreach \l [count=\i] in {1,2,3,4,5,6,k}
  \node [above] at (hidden-\i.north) {$H_{d\l}$};    
}    
\foreach \l [count=\i] in {1,2,3,n}
  \draw [->] (output-\i) -- ++(1,0)
    node [above, midway] {$Y_{\l}$};

\foreach \i in {1,...,4}
  \foreach \j in {1,...,7}
    \draw [->] (input-\i) -- (hidden-\j);

\foreach \i in {1,...,7}
  \foreach \j in {1,...,4}
    \draw [->] (hidden-\i) -- (output-\j);


\end{tikzpicture}

\end{document} 

Code is based on https://www.overleaf.com/latex/examples/neural-network-color/jwsbrhgwmgmt#.WyDQpKczbIV

I really appricate your help. Thank you.

Answer 1

Well, that happens if someone writes a nice code and others extend it without knowing what they are doing. If everyone in that chain would reveal the source of the code, this exercise would not become so painful. In particular, I would have found Torbjørn T.'s nice code much earlier. UPDATE: After some (devastating ;-) feedback from @J Leon V. and @Skillmon (thanks, BTW) I tried to structure the code a bit. Ah, and now everything is taken care of by a single macro, and layers also get labeled.

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{positioning}
\begin{document}

\tikzset{%
   neuron missing/.style={
    draw=none, 
    scale=2,
    text height=0.333cm,
    execute at begin node=\color{black}$\vdots$
  },
}

% The command \DrawNeuronalNetwork has a list as argument, each entry is a
% layer. each entry has the form 
%  Layer name/number of nodes/color/missing node/label/symbolic number
% where
% * layer name is, well,  the name of the layer
% * number of nodes is the number of neurons in that layer (including the missing neuron)
% * color is the color of the layer
% * missing node denotes the index of the missing neuron
% * label denotes the label of the layer
% * symbolic number denotes the symbol that indicates how many neurons there are

\newcommand{\DrawNeuronalNetwork}[2][]{
\xdef\Xmax{0}
\foreach \Layer/\X/\Col/\Miss/\Lab/\Count [count=\Y] in {#2}
{\pgfmathsetmacro{\Xmax}{max(\X,\Xmax)}
 \xdef\Xmax{\Xmax}
 \xdef\Ymax{\Y}
}
\foreach \Layer/\X/\Col/\Miss/\Lab/\Count [count=\Y] in {#2}
{\node[anchor=south] at ({2*\Y},{\Xmax/2+0.1}) {\Layer};
 \foreach \m in {1,...,\X}
 {
  \ifnum\m=\Miss
   \node [neuron missing] (neuron-\Y-\m) at ({2*\Y},{\X/2-\m}) {};
  \else
   \node [circle,fill=\Col!50,minimum size=1cm] (neuron-\Y-\m) at 
  ({2*\Y},{\X/2-\m}) {};
 \ifnum\Y=1
  \else
   \pgfmathtruncatemacro{\LastY}{\Y-1}
   \foreach \Z in {1,...,\LastX}
   {
    \ifnum\Z=\LastMiss
    \else
     \draw[->] (neuron-\LastY-\Z) -- (neuron-\Y-\m);
    \fi
    }
  \fi
 \fi
 \ifnum\Y=1
  \ifnum\m=\X
   \draw [<-] (neuron-\Y-\m) -- ++(-1,0) node [above, midway] {$\Lab_{\Count}$};
  \else
   \ifnum\m=\Miss
   \else
    \draw [<-] (neuron-\Y-\m) -- ++(-1,0) node [above, midway] {$\Lab_{\m}$};
   \fi
  \fi
 \else
   \ifnum\Y=\Ymax
    \ifnum\m=\X
     \draw [->] (neuron-\Y-\m) -- ++(1,0) node [above, midway] {$\Lab_{\Count}$};
    \else
     \ifnum\m=\Miss
     \else
      \draw [->] (neuron-\Y-\m) -- ++(1,0) node [above, midway] {$\Lab_{\m}$};
     \fi
    \fi
   \else
     \ifnum\m=1
      \node[above=0pt of neuron-\Y-\m] {$\Lab_1$};
     \fi
     \ifnum\m=\X
      \node[below=0pt of neuron-\Y-\m] {$\Lab_{\Count}$};
     \fi
   \fi
 \fi     
 }
 \xdef\LastMiss{\Miss}
 \xdef\LastX{\X}
}
}
\begin{tikzpicture}[x=1.5cm, y=1.5cm, >=stealth,font=\sffamily]
\DrawNeuronalNetwork{Input Layer/5/green/4/X/n,
Mapping Layer/7/red/4/H/k,
Bottleneck Layer/3/blue/2/T/f,
Demapping Layer/7/red/4/G/f,
Output Layer/5/green/4/Y/n}
\end{tikzpicture}
\end{document}