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OOP approach to creating a predictive model using perceptron learning in Python.
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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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