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@carlomazzaferro
Last active February 1, 2017 07:59
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OOP approach to creating a predictive model using perceptron learning in Python.
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
class Perceptron(object):
def __init__(self, train, labels, learning_rate, iterations):
self.train = train
self.labels = labels
self.weights = numpy.random.rand(len(self.train[0])) - 0.5 # some rand values
self.bias = numpy.random.rand() - 0.5
self.max_iter = iterations
self.l_rate = learning_rate
self.total_error = 0
self.round_errors = [] # for plotting
def train_weights(self):
_learned = False
_round = 1
while not _learned:
self.total_error = 0
for idx, row in enumerate(self.train):
prediction = self.predict(row)
error = self.labels[idx] - prediction
self.update_weights(row, error)
self.update_total_error(error)
self.update_bias(error)
self.round_errors.append((_round, abs(self.total_error)))
print('Round=%i, lrate=%.3f, error=%.3f' % (_round, self.l_rate, abs(self.total_error)))
_round += 1
if self.total_error == 0.0 or _round >= self.max_iter: # stop criteria
print('# Rounds', _round)
_learned = True # stop learning
def update_bias(self, error):
self.bias += self.l_rate * error
def update_total_error(self, error):
self.total_error += error
def update_weights(self, row, err):
for i in range(len(self.weights)):
self.weights[i] += self.l_rate * err * row[i]
# dot product of weigths and x
def predict(self, row):
output = 0
for i in range(len(self.weights)):
output += self.weights[i] * row[i] + self.bias
return self.determine_pred(output)
@staticmethod
def determine_pred(output):
return 1.0 if output >= 0.0 else -1.0
@staticmethod
def plot(err):
iteration = np.array([e[0] for e in err])
error = np.array([e[1] for e in err])
plt.plot(iteration, error)
plt.xlabel('Round Number')
plt.ylabel('Absolute Error')
plt.title('Total Error By Round')
plt.show()
if __name__ == '__main__':
X_train, Y_train, X_test, Y_test = digest('Q1_data.txt')
pcp = Perceptron(X_train, Y_train, 0.001, 100)
pcp.train_weights()
print('Weights: %f, %f, %f' % (pcp.weights[0], pcp.weights[1], pcp.weights[2]))
print('Bias: %f' % pcp.bias)
pcp.plot(pcp.round_errors) #shown in report
#Outputs:
"""
Round=1, lrate=0.001, error=6.000
Round=2, lrate=0.001, error=2.000
Round=3, lrate=0.001, error=2.000
Round=4, lrate=0.001, error=2.000
Round=5, lrate=0.001, error=0.000
# Rounds 6
Weights: 0.559600, -0.471400, 0.141200
Bias: -0.688000
"""
#Predict and calculate test error
test_error = 0
for i, row in enumerate(X_test):
test_error += abs(pcp.predict(row) - Y_test[i][0])
print('Cumulative Test Error: %f' % test_error)
#Output
"""
Cumulative Test Error: 0.000000
"""
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