Mfcttrf

Below is my MWE.
I understand the gist of tikz and foreachs, but when it comes to variables I don't understand most yet.

I want an arrow pointing from each cell to a module, and them from the module to the cluster output.

As you can see, I got the loop going, but I don't know how to get random numbers. I get rand to work, but that produces the output you can see below.

I thought about 2 ways:

1. Make an if statement to check what number the rand number is and link that to the modules.
   E.G rand == 1 -> Module 1; rand == 2 Module 2; rand == 3 Module 875 etc.
   I dont get it to work like ifnumrand=1




2. Get a random number from a set.

I'd prefer method 2, but if you can give me any tips on how to do either I'm glad!

Any help appreciated!

documentclass[
a4paper, % Papierformat A4
12pt, % Schrift 12-Punkt
headsepline, % mit Linie unter der Kopfzeile
numbers=noenddot, % Nummern ohne Punkt am Ende
bibliography=totoc, % Literaturverzeichnis mit Nummer im 
Inhaltsverzeichnis (``TO Table Of Contents'')
index=totoc, % Index mit Nummer im Inhaltsverzeichnis
fleqn, % Formeln werden linksbündig statt zentriert 
angeordnet
headings=normal % Etwas kleinere Überschriften
]scrreprt
usepackagetikz
usepackagesubfigure
usepackageadjustbox
usepackagegraphics
usepackage[first=1, last=4]lcg
usetikzlibrarymatrix, positioning



begindocument

 beginfigure[!htb]

 begintikzpicture[font=sffamily]
 matrix[matrix of nodes, nodes in empty cells, column sep=-pgflinewidth, row sep=-pgflinewidth,
 nodes = minimum height=7mm, minimum width=1cm, anchor=center, draw, fill=white, inner sep=0, outer sep = 0,
 %column 1/.style=nodes=fill=orange,
 %row 1/.style=nodes=fill=green,
 %row 1 column 1/.style=nodes=draw=none, fill=none,
 w/.style=fill=white,
 label=above:Digi Input] (Clusters) 
 &&&&&&&&&&&&&&&\[10cm]
 ;

 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (-6.5,-4) Modul 1;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (-2.5,-4) Modul 2;
 node[ minimum height=4cm,minimum width=3cm] at (0,-4) $cdots$;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (2.5,-4) Modul 875;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (6.5,-4) Modul 876;
 pgfmathdeclarerandomlistmodules-6.5-2.52.56.5
 %foreach x in 1,2,...,5
 newcountermyrandomrand
 foreach x in -7.5, -6.5,..., 7.5
 %rand;
 pgfmathrandomitemnummodules
 draw [->, line width=0.5mm] (x,-0.35) -- (num,-2);
 %draw [fill=gray] (-8,-4) rectangle (-6,-1);
 %draw [->, line width=0.5mm] (-7.5,-0.35) -- (-7,-0.95);
 %node[font=Hugesffamily, draw] Skippd;
 %node[font=Hugesffamily, below left=0pt of Clusters-3-14.north east] Skipped;



 matrix[matrix of nodes, nodes in empty cells, column sep=-pgflinewidth, row sep=-pgflinewidth,
 nodes = minimum height=7mm, minimum width=1cm, anchor=center, draw, fill=white,
 %column 1/.style=nodes=fill=orange,
 %row 1/.style=nodes=fill=green,
 %row 1 column 1/.style=nodes=draw=none, fill=none,
 w/.style=fill=white,
 label=below:Cluster Output] at (0,-8)(Cluster Output) 
 &&&&&&&&&&&&&&&\
 ;
 endtikzpicture
 begintikzpicture[font=sffamily]
 matrix[matrix of nodes, nodes in empty cells, column sep=-pgflinewidth, row sep=-pgflinewidth,
 nodes = minimum height=7mm, minimum width=1cm, anchor=center, draw, fill=white, inner sep=0, outer sep = 0,
 %column 1/.style=nodes=fill=orange,
 %row 1/.style=nodes=fill=green,
 %row 1 column 1/.style=nodes=draw=none, fill=none,
 w/.style=fill=white,
 label=above:Digi Input] (Clusters) 
 &&&&&&&&&&&&&&&\[10cm]
 ;

 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (-6.5,-4) Modul 1;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (-2.5,-4) Modul 2;
 node[ minimum height=4cm,minimum width=3cm] at (0,-4) $cdots$;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (2.5,-4) Modul 875;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] at (6.5,-4) Modul 876;

 %draw [->, line width=0.5mm] (-7.5,-0.35) -- (-6.5,-2);
 %draw [fill=gray] (-8,-4) rectangle (-6,-1);
 %draw [->, line width=0.5mm] (-7.5,-0.35) -- (-7,-0.95);
 %node[font=Hugesffamily, draw] Skippd;
 %node[font=Hugesffamily, below left=0pt of Clusters-3-14.north east] Skipped;



 matrix[matrix of nodes, nodes in empty cells, column sep=-pgflinewidth, row sep=-pgflinewidth,
 nodes = minimum height=7mm, minimum width=1cm, anchor=center, draw, fill=white,
 %column 1/.style=nodes=fill=orange,
 %row 1/.style=nodes=fill=green,
 %row 1 column 1/.style=nodes=draw=none, fill=none,
 w/.style=fill=white,
 label=below:Cluster Output] at (0,-8)(Cluster Output) 
 &&&&&&&&&&&&&&&\
 ;
 endtikzpicture
 captionLokale Rekonstruktion
 endfigure
enddocument

pgf comes with a tool that selects a random item from a list. In your example, one can do, as you said

pgfmathdeclarerandomlistmodules1234
pgfmathrandomitemnummodules

This is to summarize our conversation in the comments. As for your question: "Do you maybe have any quick idea how to stop the arrows from overlapping so much?": No, I do not have a magical tool that disentangles the arrows. What I can offer is something that makes the arrow color depend on the module and the angles of the incoming arrows arguably a bit nicer.

documentclass[
a4paper, % Papierformat A4
12pt, % Schrift 12-Punkt
headsepline, % mit Linie unter der Kopfzeile
numbers=noenddot, % Nummern ohne Punkt am Ende
bibliography=totoc, % Literaturverzeichnis mit Nummer im 
Inhaltsverzeichnis (``TO Table Of Contents'')
index=totoc, % Index mit Nummer im Inhaltsverzeichnis
fleqn, % Formeln werden linksbündig statt zentriert 
angeordnet
headings=normal % Etwas kleinere Überschriften
]scrreprt
usepackagetikz
usetikzlibrarymatrix, positioning,calc

begindocument
beginfigure[!htb]
begintikzpicture[font=sffamily]
 matrix[matrix of nodes, nodes in empty cells, column sep=-pgflinewidth, row sep=-pgflinewidth,
 nodes = minimum height=7mm, minimum width=1cm, anchor=center, draw, fill=white, inner sep=0, outer sep = 0,
 %column 1/.style=nodes=fill=orange,
 %row 1/.style=nodes=fill=green,
 %row 1 column 1/.style=nodes=draw=none, fill=none,
 w/.style=fill=white,
 label=above:Digi Input] (Clusters) 
 &&&&&&&&&&&&&&&\[10cm]
 ;

 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm]
 (module-1) at (-6.5,-4) Modul 1;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] 
 (module-2) at (-2.5,-4) Modul 2;
 node[ minimum height=4cm,minimum width=3cm] at (0,-4) $cdots$;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] 
 (module-3) at (2.5,-4) Modul 875;
 node[draw, shape=rectangle, minimum height=4cm,minimum width=3cm] 
 (module-4)at (6.5,-4) Modul 876;



 matrix[matrix of nodes, nodes in empty cells, column sep=-pgflinewidth, row sep=-pgflinewidth,
 nodes = minimum height=7mm, minimum width=1cm, anchor=center, draw, fill=white,
 %column 1/.style=nodes=fill=orange,
 %row 1/.style=nodes=fill=green,
 %row 1 column 1/.style=nodes=draw=none, fill=none,
 w/.style=fill=white,
 label=below:Cluster Output] at (0,-8)(Cluster Output) 
 &&&&&&&&&&&&&&&\
 ;

 pgfmathdeclarerandomlistmodules1234
 edefLstColors"black","red","green!70!black","blue"
 foreach Y in 1,...,16
 %rand;
 pgfmathrandomitemnummodules
 pgfmathsetmacromycolorLstColors[num-1]
 path (Clusters-1-Y.south) -- (module-num.90-2*Y+17)
 coordinate[pos=0.4] (aux0) coordinate[pos=0.5] (aux1);
 draw [-latex,thick,mycolor] let p1=($(aux1)-(aux0)$),
 n1=atan2(y1,x1) in 
 (Clusters-1-Y.south) to[out=-90,in=n1+180]
 (aux0) -- (aux1) to[out=n1,in=90] (module-num.90-4*Y+34);
% 
% foreach X in 1,2,875,876
% foreach Y in 1,...,16
% draw[-latex,thick] (Clusters-1-Y.south) to (module-X.north);
% draw[-latex,thick] (module-X.south) to (Cluster Output-1-Y.north);

 endtikzpicture
 captionLokale Rekonstruktion
 endfigure
enddocument

If you replace the loop by

pgfmathdeclarerandomlistmodules1234
edefLstColors"black","red","green!70!black","blue"
foreach Y in 1,...,16
 %rand;
 pgfmathrandomitemnummodules
 pgfmathsetmacromycolorLstColors[num-1]
 draw[thick,-latex,mycolor] (Clusters-1-Y.south) 
 to[out=-90,in=90,looseness=0.3] (module-num.90-4*Y+34); 

you get