ResNet


In [1]:
#Load necessary libraries
import tensorflow as tf
import numpy as np
import tensorflow.contrib.slim as slim
import input_data
import matplotlib.pyplot as plt
%matplotlib inline

Load CIFAR Dataset

To obtain the CIFAR10 dataset, go here: https://www.cs.toronto.edu/~kriz/cifar.html

The training data is stored in 5 separate files, and we will alternate between them during training.


In [2]:
def unpickle(file):
    import cPickle
    fo = open(file, 'rb')
    dict = cPickle.load(fo)
    fo.close()
    return dict

def ConvertImages(raw):
    """
    Convert images from the CIFAR-10 format and
    return a 4-dim array with shape: [image_number, height, width, channel]
    where the pixels are floats between 0.0 and 1.0.
    """

    # Convert the raw images from the data-files to floating-points.
    raw_float = np.array(raw, dtype=float) / 255.0

    # Reshape the array to 4-dimensions.
    images = raw_float.reshape([-1, 3, 32, 32])

    # Reorder the indices of the array.
    images = images.transpose([0, 2, 3, 1])

    return images

In [3]:
currentCifar = 1
cifar = unpickle('./cifar10/data_batch_1')
cifarT = unpickle('./cifar10/test_batch')

In [4]:
total_layers = 25 #Specify how deep we want our network
units_between_stride = total_layers / 5

ResNet

An implementation of a Residual Network as described in Identity Mappings in Deep Residual Networks.


In [5]:
def resUnit(input_layer,i):
    with tf.variable_scope("res_unit"+str(i)):
        part1 = slim.batch_norm(input_layer,activation_fn=None)
        part2 = tf.nn.relu(part1)
        part3 = slim.conv2d(part2,64,[3,3],activation_fn=None)
        part4 = slim.batch_norm(part3,activation_fn=None)
        part5 = tf.nn.relu(part4)
        part6 = slim.conv2d(part5,64,[3,3],activation_fn=None)
        output = input_layer + part6
        return output

tf.reset_default_graph()

input_layer = tf.placeholder(shape=[None,32,32,3],dtype=tf.float32,name='input')
label_layer = tf.placeholder(shape=[None],dtype=tf.int32)
label_oh = slim.layers.one_hot_encoding(label_layer,10)

layer1 = slim.conv2d(input_layer,64,[3,3],normalizer_fn=slim.batch_norm,scope='conv_'+str(0))
for i in range(5):
    for j in range(units_between_stride):
        layer1 = resUnit(layer1,j + (i*units_between_stride))
    layer1 = slim.conv2d(layer1,64,[3,3],stride=[2,2],normalizer_fn=slim.batch_norm,scope='conv_s_'+str(i))
    
top = slim.conv2d(layer1,10,[3,3],normalizer_fn=slim.batch_norm,activation_fn=None,scope='conv_top')

output = slim.layers.softmax(slim.layers.flatten(top))

loss = tf.reduce_mean(-tf.reduce_sum(label_oh * tf.log(output) + 1e-10, axis=[1]))
trainer = tf.train.AdamOptimizer(learning_rate=0.001)
update = trainer.minimize(loss)

Visualize the network graph

We can call the Tensorflow Board to provide a graphical representation of our network.


In [8]:
from IPython.display import clear_output, Image, display, HTML

def strip_consts(graph_def, max_const_size=32):
    """Strip large constant values from graph_def."""
    strip_def = tf.GraphDef()
    for n0 in graph_def.node:
        n = strip_def.node.add() 
        n.MergeFrom(n0)
        if n.op == 'Const':
            tensor = n.attr['value'].tensor
            size = len(tensor.tensor_content)
            if size > max_const_size:
                tensor.tensor_content = "<stripped %d bytes>"%size
    return strip_def

def show_graph(graph_def, max_const_size=32):
    """Visualize TensorFlow graph."""
    if hasattr(graph_def, 'as_graph_def'):
        graph_def = graph_def.as_graph_def()
    strip_def = strip_consts(graph_def, max_const_size=max_const_size)
    code = """
        <script>
          function load() {{
            document.getElementById("{id}").pbtxt = {data};
          }}
        </script>
        <link rel="import" href="https://tensorboard.appspot.com/tf-graph-basic.build.html" onload=load()>
        <div style="height:600px">
          <tf-graph-basic id="{id}"></tf-graph-basic>
        </div>
    """.format(data=repr(str(strip_def)), id='graph'+str(np.random.rand()))

    iframe = """
        <iframe seamless style="width:1200px;height:620px;border:0" srcdoc="{}"></iframe>
    """.format(code.replace('"', '&quot;'))
    display(HTML(iframe))

In [9]:
show_graph(tf.get_default_graph().as_graph_def())