04_linreg_eager_starter.py

""" Starter code for a simple regression example using eager execution.
Created by Akshay Agrawal (akshayka@cs.stanford.edu)
CS20: "TensorFlow for Deep Learning Research"
cs20.stanford.edu
Lecture 04
"""
import time

import tensorflow as tf
import tensorflow.contrib.eager as tfe
import matplotlib.pyplot as plt

import utils

DATA_FILE = 'data/birth_life_2010.txt'

# In order to use eager execution, `tfe.enable_eager_execution()` must be
# called at the very beginning of a TensorFlow program.
#############################
########## TO DO ############
#############################

# Read the data into a dataset.
data, n_samples = utils.read_birth_life_data(DATA_FILE)
dataset = tf.data.Dataset.from_tensor_slices((data[:,0], data[:,1]))

# Create weight and bias variables, initialized to 0.0.
#############################
########## TO DO ############
#############################
w = None
b = None

# Define the linear predictor.
def prediction(x):
  #############################
  ########## TO DO ############
  #############################
  pass

# Define loss functions of the form: L(y, y_predicted)
def squared_loss(y, y_predicted):
  #############################
  ########## TO DO ############
  #############################
  pass

def huber_loss(y, y_predicted):
  """Huber loss with `m` set to `1.0`."""
  #############################
  ########## TO DO ############
  #############################
  pass

def train(loss_fn):
  """Train a regression model evaluated using `loss_fn`."""
  print('Training; loss function: ' + loss_fn.__name__)
  optimizer = tf.train.GradientDescentOptimizer(learning_rate=0.01)

  # Define the function through which to differentiate.
  #############################
  ########## TO DO ############
  #############################
  def loss_for_example(x, y):
    pass

  # Obtain a gradients function using `tfe.implicit_value_and_gradients`.
  #############################
  ########## TO DO ############
  #############################
  grad_fn = None

  start = time.time()
  for epoch in range(100):
    total_loss = 0.0
    for x_i, y_i in tfe.Iterator(dataset):
      # Compute the loss and gradient, and take an optimization step.
      #############################
      ########## TO DO ############
      #############################
      optimizer.apply_gradients(gradients)
      total_loss += loss
    if epoch % 10 == 0:
      print('Epoch {0}: {1}'.format(epoch, total_loss / n_samples))
  print('Took: %f seconds' % (time.time() - start))
  print('Eager execution exhibits significant overhead per operation. '
        'As you increase your batch size, the impact of the overhead will '
        'become less noticeable. Eager execution is under active development: '
        'expect performance to increase substantially in the near future!')

train(huber_loss)
plt.plot(data[:,0], data[:,1], 'bo')
# The `.numpy()` method of a tensor retrieves the NumPy array backing it.
# In future versions of eager, you won't need to call `.numpy()` and will
# instead be able to, in most cases, pass Tensors wherever NumPy arrays are
# expected.
plt.plot(data[:,0], data[:,0] * w.numpy() + b.numpy(), 'r',
         label="huber regression")
plt.legend()
plt.show()