# feature vector of NN

2 views (last 30 days)
Yogini Prabhu on 31 Dec 2020
Commented: Yogini Prabhu on 10 Jan 2021
how to find the feature vector of NN in the attached results obtained from the nprtool (which is app for develop pattern recognition appalication of Neural network).
Athul Prakash on 8 Jan 2021
I'm not aware of a single function or a direct way to extract intermediate layer outputs, but I have suggested a couple of workarounds in my answer below.
Yogini Prabhu on 10 Jan 2021
thanks i will try those

Athul Prakash on 8 Jan 2021
Edited: Athul Prakash on 8 Jan 2021
You can extract the network and inputs from the 'results' struct using..
net = results.net
inputs = results.inputs
I found 2 ways to extract activations from intermediate layers in a 'network' object :-
Approach 1
You may modify the architecture to specify the required layer as an outputLayer..
% Say 'net' is the network. Assume you want the output of layer 'i'.
net.outputConnect(i) = 1 % Modifies the architecture to set layer 'i' as an additional output.
out = sim(net, inputs) % the activations of i-th layer are now included in the output vector.
Approach 2
Manually run the neural network by executing it's underlying maths.
Suppose you're trying to get the outputs of layer 3...
X = inputs; % Initialize 'X' as inputs. Each layer's values will be computer into 'X'.
% Layer 1
X = net.IW{1,1} * X + net.b{1}; % Compute the values of layer 1. Use 'net.IW' (input weights)
X = tansig(X) % apply whichever is the activation function of layer 1.
% Layer 2
X = net.LW{2,1} * X + net.b{2}; % compute the values of layer 2. Use 'net.LW' (layer weights)
X = logsig(X) % apply whichever is the activation function of layer 2.
% layer 3
X = net.LW{3,2} * X + net.b{3} % same of for layer 2
X = softmax(X) % apply whichever is the activation function of layer 3.
% 'X' now contains the activations of the third layer in the network.
The manual computation might require tinkering with the 'network' object's many properties. You may follow the attached documentation to get a better understanding of these properties and how to manipulate them.
Hope it Helps!

### Categories

Find more on Image Data Workflows in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!