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Updated bias values while training #10

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Updated bias values while training #10

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6905b12
Added update to bias while training
priyadesh99 Apr 7, 2021
ae88e5e
Merge pull request #1 from PriyaDeshpande1605/PriyaDeshpande1605-with…
priyadesh99 Apr 7, 2021
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21 changes: 6 additions & 15 deletions neural-network.py
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Original file line number Diff line number Diff line change
@@ -1,21 +1,6 @@
import random
import math

#
# Shorthand:
# "pd_" as a variable prefix means "partial derivative"
# "d_" as a variable prefix means "derivative"
# "_wrt_" is shorthand for "with respect to"
# "w_ho" and "w_ih" are the index of weights from hidden to output layer neurons and input to hidden layer neurons respectively
#
# Comment references:
#
# [1] Wikipedia article on Backpropagation
# http://en.wikipedia.org/wiki/Backpropagation#Finding_the_derivative_of_the_error
# [2] Neural Networks for Machine Learning course on Coursera by Geoffrey Hinton
# https://class.coursera.org/neuralnets-2012-001/lecture/39
# [3] The Back Propagation Algorithm
# https://www4.rgu.ac.uk/files/chapter3%20-%20bp.pdf

class NeuralNetwork:
LEARNING_RATE = 0.5
Expand Down Expand Up @@ -98,6 +83,9 @@ def train(self, training_inputs, training_outputs):
# Δw = α * ∂Eⱼ/∂wᵢ
self.output_layer.neurons[o].weights[w_ho] -= self.LEARNING_RATE * pd_error_wrt_weight

pd_errors_wrt_weight = pd_errors_wrt_output_neuron_total_net_input[o] * 1
self.output_layer.neurons[o].bias -= self.LEARNING_RATE * pd_error_wrt_weight

# 4. Update hidden neuron weights
for h in range(len(self.hidden_layer.neurons)):
for w_ih in range(len(self.hidden_layer.neurons[h].weights)):
Expand All @@ -108,6 +96,9 @@ def train(self, training_inputs, training_outputs):
# Δw = α * ∂Eⱼ/∂wᵢ
self.hidden_layer.neurons[h].weights[w_ih] -= self.LEARNING_RATE * pd_error_wrt_weight

pd_errors_wrt_weight = pd_errors_wrt_hidden_neuron_total_net_input[o] * 1
self.hidden_layer.neurons[o].bias -= self.LEARNING_RATE * pd_error_wrt_weight

def calculate_total_error(self, training_sets):
total_error = 0
for t in range(len(training_sets)):
Expand Down