Using the BackpropagationNet class
Features of the BackpropagationNet class
| Number of neuron layers | minimum: 2, maximum: N |
| Number of neurons in each layer | minimum: 1, maximum: N |
| Weight matrices | Automatically created and initialized. The weights are connecting the neurons of two consecutive layers |
| Bias values | Automatically used |
| Number of input/target patterns | minimum: 1, maximum: N |
| One learning step includes | Forward propagation and backpropagation of all input patterns (learning-by-epoch), changing of the weights |
Steps to create a Backpropagation Net
1. Object declaration
BackpropagationNet bpn;
Required. Declares the object bpn to be of type BackpropagationNet.
2. Constructor call
bpn = new BackpropagationNet();
Required. Creates an instance of BackpropagationNet. This is the only constructor of the class and takes no arguments.
3. Read conversion file
bpn.readConversionFile("fileName");
Required. Reads the ASCII-binary conversion file. See The structure of a conversion file for further explanation of conversion files.
4. Create input layer
bpn.addNeuronLayer(i);
Required. Creates the net's input layer with i neurons. The neuron layers are sequentially added to the net structure!
Create hidden layer(s)
bpn.addNeuronLayer(h);
Creates the net's hidden layer(s) with h neurons. This step is optional (if your net should have no hidden layers) or may be done one or more times (if your net has one or more hidden layers). If your net has more than one hidden layers, the number of neurons in each layer must not always be the same.
5. Create output layer
bpn.addNeuronLayer(o);
Required. Creates the net's output layer with o neurons.
6. Connect all layers
bpn.connectLayers();
Required. Connects the neurons of all consecutive layers. All weight matrices are created and initialized with random values.
7. Read pattern file
bpn.readPatternFile("fileName");
Required. Reads the pattern file that contains the input and target patterns. See The structure of a pattern file below for further explanation of pattern files.
Set learning rate
bpn.setLearningRate(x);
Sets the net's learning rate to x.
Set minimum error
bpn.setMinimumError(x);
Sets the net's minimum error to x. The net learns, until its error is smaller than this value.
Set accuracy
bpn.setAccuracy(x);
Sets the net's accuracy value to x.
Set maximum learning cycles
bpn.setMaxLearningCycles(x);
Sets the maximum number of learning cycles to x. The default value is -1 (no maximum).
Reset learning time
bpn.resetTime();
Resets the learning time.
8. Perform a learning cycle
bpn.learn();
Required. Performs one learning cycle. This method is usually called within a loop, which exits, if the finishedLearning() method returns true.
Recall a pattern
bpn.recall("inputPattern");
Tries to recall the correct output of the input pattern inputPattern.
Information is available on:
Accuracy
bpn.getAccuracy();
Returns the accuracy value of the net.
Elapsed time
bpn.getElapsedTime();
Returns the time that elapsed since the learning process started.
Input pattern
bpn.getInputPattern(i);
Returns the input pattern with number i. Pattern numbers start with zero!
Learning cycle
bpn.getLearningCycle();
Returns the current learning cycle of the net.
Learning rate
bpn.getLearningRate();
Returns the learning rate of the net.
Minimum error
bpn.getMinimumError();
Returns the minimum error of the net.
Net error
bpn.getError();
Returns the current error of the net.
Neuron outputs
bpn.getNeuronOutputs(i);
Returns the output values of all neurons in layer i.
Number of layers
bpn.getNumberOfLayers();
Returns the number of neuron layers.
Number of neurons
bpn.getNumberOfNeurons(i);
Returns the number of neurons in layer i. Neuron layer numbers start with zero!
Number of patterns
bpn.getNumberOfPatterns();
Returns the number of input/target patterns.
Number of all weights
bpn.getNumberOfWeights();
Returns the number of all weights.
Number of weights
bpn.getNumberOfWeights(m);
Returns the number of weights in weight matrix m.
Output pattern
bpn.getOutputPattern(i);
Returns the output pattern with number i. Pattern numbers start with zero!
Pattern error
bpn.getPatternError(i);
Returns the error of the output pattern with number i. Pattern numbers start with zero!
Target pattern
bpn.getTargetPattern(i);
Returns the target pattern with number i. Pattern numbers start with zero!
Weight values
bpn.getWeightValues(m);
Returns all weight values of weight matrix m. Weight matrix numbers start with zero!
Here is the source code of the BPN Application to show you an example: BPN.java
