linear_regression_full.py

import numpy as np
import tensorflow as tf
import matplotlib.pyplot as plt

def generate_dataset():
	x_batch = np.linspace(0, 2, 100)
	y_batch = 1.5 * x_batch + np.random.randn(*x_batch.shape) * 0.2 + 0.5
	return x_batch, y_batch

def linear_regression():
	x = tf.placeholder(tf.float32, shape=(None, ), name='x')
	y = tf.placeholder(tf.float32, shape=(None, ), name='y')

	with tf.variable_scope('lreg') as scope:
		w = tf.Variable(np.random.normal(), name='W')
		b = tf.Variable(np.random.normal(), name='b')
		
		y_pred = tf.add(tf.multiply(w, x), b)

		loss = tf.reduce_mean(tf.square(y_pred - y))

	return x, y, y_pred, loss

def run():
	x_batch, y_batch = generate_dataset()

	x, y, y_pred, loss = linear_regression()

	optimizer = tf.train.GradientDescentOptimizer(0.1)
	train_op = optimizer.minimize(loss)

	with tf.Session() as session:
		session.run(tf.global_variables_initializer())

		feed_dict = {x: x_batch, y: y_batch}
		
		for i in range(30):
			_ = session.run(train_op, feed_dict)
			print(i, "loss:", loss.eval(feed_dict))

		print('Predicting')
		y_pred_batch = session.run(y_pred, {x : x_batch})

	plt.scatter(x_batch, y_batch)
	plt.plot(x_batch, y_pred_batch, color='red')
	plt.xlim(0, 2)
	plt.ylim(0, 2)
	plt.savefig('plot.png')

if __name__ == "__main__":
	run()

Hello Derek,

I saw your article at TowardsDataScience.com; thank you.
Newbie here; if I have a spyder working enviro and I cut and paste this code I get a return of "NameError: name 'y_batch' is not defined". But it is defined in Line 7. My spyder is in Python3.7
Would you mind a brief comment to help send me on a life of enlightenment. Thanks.

T

Hello Derek,

I saw your article at TowardsDataScience.com; thank you.
Newbie here; if I have a spyder working enviro and I cut and paste this code I get a return of "NameError: name 'y_batch' is not defined". But it is defined in Line 7. My spyder is in Python3.7
Would you mind a brief comment to help send me on a life of enlightenment. Thanks.

T

Hi T,

I tried rerunning my code again and it works. Can you check if you have any indentation error? Otherwise, can you break the code into different parts and make sure each of the part runs?

Cheers,
Derek

Hello Derek,
Thank you for the detailed explanation. Can you please let me know how to extract the Slope and Bias from the Best Fit Line (Red Line in your plot). Thanks!