How to Visualize a Neural Network in Python using Graphviz ?

Last Updated : 24 Jan, 2021

In this article, We are going to see how to plot (visualize) a neural network in python using Graphviz. Graphviz is a python module that open-source graph visualization software. It is widely popular among researchers to do visualizations. It’s representing structural information as diagrams of abstract graphs and networks means you only need to provide an only textual description of the graph regarding its topological structure and this will automatically read and create an image.

Installation:

For window terminal:

pip install graphviz

For anaconda terminal:

conda install -c anaconda graphviz

Plotting a simple graph with Graphviz

Approach:

Import module.
Create a new object of Diagraph.
Add node() and edge() into graph object.
Save the source code with render() object.

Below is the implementation:

Python3

# import module 
from graphviz import Digraph 
  
# instantiating object 
dot = Digraph(comment='A Round Graph') 
  
# Adding nodes 
dot.node('A', 'Alex') 
dot.node('B', 'Rishu') 
dot.node('C', 'Mohe') 
dot.node('D', 'Satyam') 
  
# Adding edges 
dot.edges(['AB', 'AC', 'AD']) 
dot.edge('B', 'C', constraint = 'false') 
dot.edge('C', 'D', constraint = 'false') 
  
# saving source code 
dot.format = 'png'
dot.render('Graph', view = True)  

Output:

Graph.png

We can check the generated source code with dot.source methods:

Python3

print(dot.source)

Output:

// A Round Graph
digraph {
    A [label=Alex]
    B [label=Rishu]
    C [label=Mohe]
    D [label=Satyam]
    A -> B
    A -> C
    A -> D
    B -> C [constraint=false]
    C -> D [constraint=false]
}

Plotting (visualize) a neural network with Graphviz

Here we are using source code for implementation which we see in the above examples:

Let’s discussed the approach:

Create a digraph object.
Define the direction of the graph using rankdir.
Create a subgraph with the following things:
- Set color.
- Set node properties.
- Set Level of the subgraph
Create the edge of between the object with (->).

This source code must be saved in a .txt file(myfile.txt) and run `dot -Tpng -O myfile.txt` from the command-line to get a .png figure with the diagram.

Example 1:

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 x4;
        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;
    x4 -> a12;
        x4 -> a22;
        x4 -> a32;
    

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

}

Run this into the terminal:

dot -Tpng -O myfile.txt

Output:

Example 2:

digraph G {

        rankdir=LR
    splines=line
        nodesep=.05;
        
        node [label=""];
        
        subgraph cluster_0 {
        color=white;
                node [style=solid,color=blue4, shape=circle];
        x1 x2 x3;
        label = "layer 1";
    }

    subgraph cluster_1 {
        color=white;
        node [style=solid,color=red2, shape=circle];
        a12 a22 a32 a42 a52;
        label = "layer 2";
    }

    subgraph cluster_2 {
        color=white;
        node [style=solid,color=red2, shape=circle];
        a13 a23 a33 a43 a53;
        label = "layer 3";
    }

    subgraph cluster_3 {
        color=white;
        node [style=solid,color=seagreen2, shape=circle];
        O1 O2 O3 O4;
        label="layer 4";
    }

        x1 -> a12;
        x1 -> a22;
        x1 -> a32;
        x1 -> a42;
        x1 -> a52;

        x2 -> a12;
        x2 -> a22;
        x2 -> a32;
        x2 -> a42;
        x2 -> a52;
 
        x3 -> a12;
        x3 -> a22;
        x3 -> a32;
        x3 -> a42;
        x3 -> a52;

        a12 -> a13
        a22 -> a13
        a32 -> a13
        a42 -> a13
        a52 -> a13

        a12 -> a23
        a22 -> a23
        a32 -> a23
        a42 -> a23
        a52 -> a23

        a12 -> a33
        a22 -> a33
        a32 -> a33
        a42 -> a33
        a52 -> a33

        a12 -> a43
        a22 -> a43
        a32 -> a43
        a42 -> a43
        a52 -> a43

        a12 -> a53
        a22 -> a53
        a32 -> a53
        a42 -> a53
        a52 -> a53

        a13 -> O1
    a23 -> O2
    a33 -> O3
    a43 -> O4
        a53 -> O4

}

Output: