Gradient Descent

gradient_descent.py

import numpy as np

X = [0.5, 2.5]
Y = [0.2, 0.9]

def f(w, b, x):
	return 1.0/(1.0 + np.exp(-(w*x + b)))

def error(w, b):
	err = 0.0
	for x,y in data:
		fx = f(w,b,x)
		err += 0.5 * (fx - y) ** 2
	return err

def grad_b(w, b, x, y):
	fx = f(w,b,x)
	return (fx-y) * fx * (1 - fx)
	
def grad_w(w, b, x, y):
	fx = f(w,b,x)
	return (fx-y) * fx * (1 - fx) * x
	
def do_gradient_descent():
	w, b, eta, max_epochs = 1, 1, 0.01, 100
	for i in range(max_epochs):
		dw, db = 0, 0
		for x,y in zip(X, Y):
			dw += grad_w(w, b, x, y)
			db += grad_b(w, b, x, y)
		w = w - eta * dw
		b = b - eta * db
	print(error(w,b))

Intially i got the error at line 11
I changed data to zip(x,y)
but i am not getting any results.
Not getting values of error. Please help me
Please also include the code to plot the graph which you have explain in your blog