Weightspace for perceptron training

train.py

# Based on https://www.cs.toronto.edu/~rgrosse/courses/csc321_2018/homeworks/hw2.pdf, 1. b.

import numpy
import pylab
import random

# Training Data

x = numpy.array([
    [1, -2],
    [0, -1]
])

N = len(x)
i = 0

w = [0, 0]

t = [1, -1]

lastnudge = N - 1

path = numpy.array([w])

for safety in range(1, 100):
    zi = numpy.matmul(numpy.transpose(w), x[i])
    if zi * t[i] <= 0:
        #print ("Nudge")
        w = w + t[i] * x[i]
        #print (w)
        lastnudge = i
        path = numpy.append(path, [w], axis=0)
    else:
        # print("No nudge")
        if (lastnudge == i):
            break
    i = (i + 1) % N
    

#plotting stuff:
pylab.title("Weight Space of Perceptron Training ($n = " + str(len(path)) + "$ steps)")
pylab.plot(path[:,0],path[:,1])
pylab.xlim(-5, 5)
pylab.ylim(-5, 5)
pylab.axhline(0, color='black', linewidth=.5)
pylab.axvline(0, color='black', linewidth=.5)
pylab.savefig("rand_walk"+str(n)+".png",bbox_inches="tight",dpi=600)
pylab.show()