multilayer_perceptron.py

'''
A Multilayer Perceptron implementation example using TensorFlow library.
This example is using the MNIST database of handwritten digits
(http://yann.lecun.com/exdb/mnist/)

Author: Aymeric Damien
Project: https://github.com/aymericdamien/TensorFlow-Examples/
'''

from __future__ import print_function

# Import MNIST data
from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets("/tmp/data/", one_hot=True)

import tensorflow as tf

# Parameters
learning_rate = 0.001
training_epochs = 15
batch_size = 100
display_step = 1

# Network Parameters
n_hidden_1 = 256 # 1st layer number of features
n_hidden_2 = 256 # 2nd layer number of features
n_input = 784 # MNIST data input (img shape: 28*28)
n_classes = 10 # MNIST total classes (0-9 digits)

with tf.device('/gpu:0'):
    # tf Graph input
    x = tf.placeholder("float", [None, n_input])
    y = tf.placeholder("float", [None, n_classes])


    # Create model
    def multilayer_perceptron(x, weights, biases):
        # Hidden layer with RELU activation
        layer_1 = tf.add(tf.matmul(x, weights['h1']), biases['b1'])
        layer_1 = tf.nn.relu(layer_1)
        # Hidden layer with RELU activation
        layer_2 = tf.add(tf.matmul(layer_1, weights['h2']), biases['b2'])
        layer_2 = tf.nn.relu(layer_2)
        # Output layer with linear activation
        out_layer = tf.matmul(layer_2, weights['out']) + biases['out']
        return out_layer

    # Store layers weight & bias
    weights = {
        'h1': tf.Variable(tf.random_normal([n_input, n_hidden_1])),
        'h2': tf.Variable(tf.random_normal([n_hidden_1, n_hidden_2])),
        'out': tf.Variable(tf.random_normal([n_hidden_2, n_classes]))
    }
    biases = {
        'b1': tf.Variable(tf.random_normal([n_hidden_1])),
        'b2': tf.Variable(tf.random_normal([n_hidden_2])),
        'out': tf.Variable(tf.random_normal([n_classes]))
    }

    # Construct model
    pred = multilayer_perceptron(x, weights, biases)

    # Define loss and optimizer
    cost = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(pred, y))
    optimizer = tf.train.AdamOptimizer(learning_rate=learning_rate).minimize(cost)

    # Initializing the variables
    init = tf.initialize_all_variables()

    # Launch the graph
    with tf.Session(config=tf.ConfigProto(log_device_placement=False)) as sess:
        sess.run(init)

        # Training cycle
        for epoch in range(training_epochs):
            avg_cost = 0.
            total_batch = int(mnist.train.num_examples/batch_size)
            # Loop over all batches
            for i in range(total_batch):
                batch_x, batch_y = mnist.train.next_batch(batch_size)
                # Run optimization op (backprop) and cost op (to get loss value)
                _, c = sess.run([optimizer, cost], feed_dict={x: batch_x,
                                                              y: batch_y})
                # Compute average loss
                avg_cost += c / total_batch
            # Display logs per epoch step
            if epoch % display_step == 0:
                print("Epoch:", '%04d' % (epoch+1), "cost=", \
                    "{:.9f}".format(avg_cost))
        print("Optimization Finished!")

        # Test model
        correct_prediction = tf.equal(tf.argmax(pred, 1), tf.argmax(y, 1))
        # Calculate accuracy
        accuracy = tf.reduce_mean(tf.cast(correct_prediction, "float"))
        print("Accuracy:", accuracy.eval({x: mnist.test.images, y: mnist.test.labels}))