chokkan

import math
import random

def train(w, D, T):
    for t in range(1, T+1):
        x, y = random.choice(D)
        a = sum([w[i] * x[i] for i in range(len(w))])             # a(x) = w \cdot x
        g = y - (1. / (1. + math.exp(-a))) if -100. < a else y    # g = y - p
        eta = 1. / t
        for i in range(len(w)):                                   # w ← w + eta * g * x

chokkan

def update(w, x, y):
    a = 0.
    for i in range(len(w)):
        a += w[i] * x[i]
    if a * y <= 0:
        for i in range(len(w)):
            w[i] += y * x[i]

def classify(w, x):
    a = 0.