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Neural_Network_Copy.py
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# -*- coding: utf-8 -*-
"""
Created on Thu Nov 8 17:44:45 2018
@author: AARUSHI
"""
"""Ref :- https://hackernoon.com/dl02-writing-a-neural-network-from-scratch-code-b32f4877c257
https://github.com/sar-gupta/neural-network-from-scratch/blob/master/neuralnetwork.py """
import numpy as np
class layer:
def __init__(self, num_nodes, layer_num,batch_size):
self.num_nodes = num_nodes
self.activation_function = "Sigmoid"
self.is_last = False
self.weight = None
self.bias = None
self.changed_weight = None
self.changed_bias = None
self.input_activation = None
if(layer_num==len(num_nodes)-1):
self.is_last = True
self.activation_function = "Softmax"
else:
self.weight = np.random.normal(0, 0.1, size=(num_nodes[layer_num], num_nodes[layer_num+1]))
self.bias = np.random.normal(0, 0.1, size=(1, num_nodes[layer_num+1]))
self.changed_weight = np.zeros((num_nodes[layer_num], num_nodes[layer_num+1]),dtype = float)
self.changed_bias = np.zeros((1, num_nodes[layer_num+1]),dtype = float)
class Neural_Network(object):
def __init__(self, nlayer, num_node, batch_size):
self.nlayer = nlayer
self.num_node= num_node
self.layers = []
self.batch_size = batch_size
for i in range(nlayer):
layer_i = layer(num_node, i,self.batch_size)
self.layers.append(layer_i)
def softmax(self, layer):
num = np.exp(layer)
den = np.sum(num)
return num/den
def sigmoid(self,x, Derivative = False):
if(Derivative):
return (x*(1.0 - x))
# return (self.sigmoid(x)*1-self.sigmoid(x))
return 1 / (1 + np.exp(-x))
def cross_entropy_derivative(self,p,y):
return (p-y)
def train(self,batch_size, input, labels,x_test,y_test, num_epochs,learning_rate, filename):
self.learning_rate = learning_rate
num_batches = int(len(input)/batch_size)
print("Started")
for i in range(num_epochs):
for j in range(num_batches):
for k in range(j*batch_size , j*batch_size+batch_size):
output = (np.zeros((self.num_node[self.nlayer-1], 1)))
output[labels[k]]=1
output = output.T
#Forward Pass
self.forward_pass(input[k])
##ORIGINAL
###self.error -= (np.sum((labels[j*batch_size : j*batch_size+batch_size] * np.log(self.layers[self.nlayer-1].input_activation ))))
#Backward Pass
self.back_pass(output)
##Gradient Descent
self.grad_descent()
print("Epoch "+str(i)+" done")
self.check_accuracy('model.pkl',x_test,y_test)
print("Training Done")
def forward_pass(self,input):
self.layers[0].input_activation = np.reshape(input,(1,input.shape[0]))
for i in range(self.nlayer-1):
first_term = np.dot(self.layers[i].input_activation,self.layers[i].weight)
second_term = self.layers[i].bias
curr_temp = np.add(first_term ,second_term)
if(self.layers[i+1].activation_function=="Sigmoid"):
self.layers[i+1].input_activation = self.sigmoid(curr_temp)
else:
self.layers[i+1].input_activation = self.softmax(curr_temp)
def back_pass(self, labels):
# if self.cost_function == "cross_entropy" and self.layers[self.num_layers-1].activation_function == "softmax":
layer = self.layers[self.nlayer-1]
prev_layer = self.layers[self.nlayer-2]
delta = self.cross_entropy_derivative(layer.input_activation,labels)
prev_layer.changed_bias += delta
prev_layer.changed_weight += np.dot(prev_layer.input_activation.T, delta)
for i in range(self.nlayer-2,0,-1):
layer = self.layers[i]
prev_layer = self.layers[i-1]
#print("jjojo")
#print(delta.shape)
#print(np.dot(delta,layer.weight.T).shape)
#print(self.sigmoid(layer.input_activation,True).T.shape)
delta = np.multiply(np.dot(delta,layer.weight.T), self.sigmoid(layer.input_activation,True))
#print(delta.shape)
#print(prev_layer.changed_bias.shape)
prev_layer.changed_bias += delta
#print(delta.shape)
#print(prev_layer.input_activation.T.shape)
#print("byeeeeeeeeeeeeeeeeeeeee")
prev_layer.changed_weight += np.dot(prev_layer.input_activation.T, delta)
def grad_descent(self):
for i in range(0,self.nlayer-1):
layer = self.layers[i]
layer.weight = layer.weight - (self.learning_rate/self.batch_size)*layer.changed_weight
layer.bias = layer.bias - (self.learning_rate/self.batch_size)*layer.changed_bias
layer.changed_weight = np.zeros((self.num_node[i], self.num_node[i+1]),dtype = float)
layer.changed_bias = np.zeros((1, self.num_node[i+1]),dtype = float)
def forward_pass_testing(self,input):
self.layers[0].input_activation = input
for i in range(self.nlayer-1):
first_term = np.dot(self.layers[i].input_activation,self.layers[i].weight)
second_term = self.layers[i].bias
curr_temp = np.add(first_term ,second_term)
if(self.layers[i+1].activation_function=="Sigmoid"):
self.layers[i+1].input_activation = self.sigmoid(curr_temp)
else:
self.layers[i+1].input_activation = self.softmax(curr_temp)
def predict(self, filename, input):
# self.batch_size = len(input)
self.forward_pass_testing(input)
a = self.layers[self.nlayer-1].input_activation
predictions = []
for i in range(len(a)):
if(a[i][0]>a[i][1]):
predictions.append(0)
else:
predictions.append(1)
return np.asarray(predictions),a
def check_accuracy(self, filename, inputs, labels):
print("Testing Started")
a, array = self.predict(filename,inputs)
total=len(a)
correct=0
for i in range(len(a)):
if (a[i] == labels[i]):
correct += 1
print("Accuracy: ", correct*100/total)