From cf3a29feb5887344b6633ead1b4b6d5657a15a4b Mon Sep 17 00:00:00 2001
From: Patrick Simianer <p@simianer.de>
Date: Sun, 15 Jun 2014 03:24:33 +0200
Subject: old stuff: algorithms

---
 algorithms/perceptron.py | 51 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 algorithms/perceptron.py

(limited to 'algorithms/perceptron.py')

diff --git a/algorithms/perceptron.py b/algorithms/perceptron.py
new file mode 100644
index 0000000..ca1ebee
--- /dev/null
+++ b/algorithms/perceptron.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python2
+
+from operator import add, mul
+
+
+def pointwise(op, x, y):
+	return [op(a, b) for (a, b) in zip(x, y)]
+
+def scalar_product(x, y):
+	"""Scalar product."""
+	return sum(pointwise(mul, x, y))
+
+def scalar_multiplication(s, v):
+	"""Scalar multiplication."""
+	return [s*i for i in v]
+
+# data extracted from corpus
+x = {1 : [ 1 , 0 , 0 , 1 , 0 , 0 , 0 , 0 , 1 ],
+     2 : [ 1 , 1 , 0 , 0 , 0 , 0 , 0 , 0 , 0 ],
+     3 : [ 0 , 1 , 0 , 1 , 1 , 0 , 0 , 0 , 0 ],
+     4 : [ 0 , 0 , 0 , 0 , 0 , 0 , 1 , 0 , 0 ],
+     5 : [ 0 , 0 , 0 , 4 , 0 , 0 , 0 , 0 , 1 ],
+     6 : [ 0 , 1 , 1 , 0 , 1 , 0 , 0 , 1 , 0 ],
+     7 : [ 0 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , 0 ],
+     8 : [ 0 , 0 , 0 , 0 , 0 , 2 , 0 , 0 , 0 ],
+     9 : [ 0 , 0 , 0 , 0 , 0 , 0 , 1 , 0 , 0 ],
+     10 : [ 0 , 0 , 0 , 0 , 0 , 2 , 0 , 0 , 2 ]}
+y = {1:1, 2:-1, 3:-1, 4:1, 5:1, 6:1, 7:1, 8:-1, 9:1, 10:-1}
+
+# learning rate
+alpha = 0.5
+# initialize parameters
+w = [0,0,0,0,0,0,0,0,0]
+rho = 0
+turn = 1
+errors = True
+
+# perceptron algorithm
+while errors:
+	print "\nTurn", turn
+	turn += 1
+	errors = False
+	for i in x.keys():
+		print "i =", i
+		trigger = y[i] * (scalar_product (w, x[i]) + rho)
+		if trigger <= 0:
+			errors = True
+			w = pointwise(add, w, scalar_multiplication(alpha*y[i],  x[i]))
+			rho += alpha*y[i]	
+			print w, rho
+
-- 
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