Graphviz script to draw a simple neural network diagram. Copy this to a `file.txt` file and then run `dot -Tpng -O file.txt` from command-line to get a .png figure with the diagram.

simple_neural_network_diagram

digraph G {

        rankdir=LR
	splines=line
        
        node [fixedsize=true, label=""];

        subgraph cluster_0 {
		color=white;
		node [style=solid,color=blue4, shape=circle];
		x1 x2 x3;
		label = "layer 1 (Input layer)";
	}

	subgraph cluster_1 {
		color=white;
		node [style=solid,color=red2, shape=circle];
		a12 a22 a32;
		label = "layer 2 (hidden layer)";
	}

	subgraph cluster_2 {
		color=white;
		node [style=solid,color=seagreen2, shape=circle];
		O;
		label="layer 3 (output layer)";
	}

        x1 -> a12;
        x1 -> a22;
        x1 -> a32;
        x2 -> a12;
        x2 -> a22;
        x2 -> a32;
        x3 -> a12;
        x3 -> a22;
        x3 -> a32;

        a12 -> O
        a22 -> O
        a32 -> O

}

You can also put it into plantuml.com's renderer, putting @startdot/@enddot around the code.

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