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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
Step1:  Image Classification
In this project, you'll classify images from the CIFAR-10 dataset.  The dataset consists of airplanes, dogs, cats, and other objects. You'll preprocess the images, then train a convolutional neural network on all the samples. The images need to be normalized and the labels need to be one-hot encoded.  You'll get to apply what you learned and build a convolutional, max pooling, dropout, and fully connected layers.  At the end, you'll get to see your neural network's predictions on the sample images.
Get the Data
Run the following cell to download the CIFAR-10 dataset for python.
Step2:  Explore the Data
The dataset is broken into batches to prevent your machine from running out of memory.  The CIFAR-10 dataset consists of 5 batches, named data_batch_1, data_batch_2, etc.. Each batch contains the labels and images that are one of the following
Step5:  Implement Preprocess Functions
Normalize
In the cell below, implement the normalize function to take in image data, x, and return it as a normalized Numpy array. The values should be in the range of 0 to 1, inclusive.  The return object should be the same shape as x.
Step8:  One-hot encode
Just like the previous code cell, you'll be implementing a function for preprocessing.  This time, you'll implement the one_hot_encode function. The input, x, are a list of labels.  Implement the function to return the list of labels as One-Hot encoded Numpy array.  The possible values for labels are 0 to 9. The one-hot encoding function should return the same encoding for each value between each call to one_hot_encode.  Make sure to save the map of encodings outside the function.
Hint
Step10:  Randomize Data
As you saw from exploring the data above, the order of the samples are randomized.  It doesn't hurt to randomize it again, but you don't need to for this dataset.
Preprocess all the data and save it
Running the code cell below will preprocess all the CIFAR-10 data and save it to file. The code below also uses 10% of the training data for validation.
Step12:  Check Point
This is your first checkpoint.  If you ever decide to come back to this notebook or have to restart the notebook, you can start from here.  The preprocessed data has been saved to disk.
Step17:  Build the network
For the neural network, you'll build each layer into a function.  Most of the code you've seen has been outside of functions. To test your code more thoroughly, we require that you put each layer in a function.  This allows us to give you better feedback and test for simple mistakes using our unittests before you submit your project.
Note
Step20:  Convolution and Max Pooling Layer
Convolution layers have a lot of success with images. For this code cell, you should implement the function conv2d_maxpool to apply convolution then max pooling
Step23:  Flatten Layer
Implement the flatten function to change the dimension of x_tensor from a 4-D tensor to a 2-D tensor.  The output should be the shape (Batch Size, Flattened Image Size). Shortcut option
Step26:  Fully-Connected Layer
Implement the fully_conn function to apply a fully connected layer to x_tensor with the shape (Batch Size, num_outputs). Shortcut option
Step29:  Output Layer
Implement the output function to apply a fully connected layer to x_tensor with the shape (Batch Size, num_outputs). Shortcut option
Step32:  Create Convolutional Model
Implement the function conv_net to create a convolutional neural network model. The function takes in a batch of images, x, and outputs logits.  Use the layers you created above to create this model
Step35:  Train the Neural Network
Single Optimization
Implement the function train_neural_network to do a single optimization.  The optimization should use optimizer to optimize in session with a feed_dict of the following
Step37:  Show Stats
Implement the function print_stats to print loss and validation accuracy.  Use the global variables valid_features and valid_labels to calculate validation accuracy.  Use a keep probability of 1.0 to calculate the loss and validation accuracy.
Step38:  Hyperparameters
Tune the following parameters
Step40:  Train on a Single CIFAR-10 Batch
Instead of training the neural network on all the CIFAR-10 batches of data, let's use a single batch. This should save time while you iterate on the model to get a better accuracy.  Once the final validation accuracy is 50% or greater, run the model on all the data in the next section.
Step42:  Fully Train the Model
Now that you got a good accuracy with a single CIFAR-10 batch, try it with all five batches.
Step45:  Checkpoint
The model has been saved to disk.
Test Model
Test your model against the test dataset.  This will be your final accuracy. You should have an accuracy greater than 50%. If you don't, keep tweaking the model architecture and parameters.
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Python Code:
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
from urllib.request import urlretrieve
from os.path import isfile, isdir
from tqdm import tqdm
import problem_unittests as tests
import tarfile
cifar10_dataset_folder_path = 'cifar-10-batches-py'
# Use Floyd's cifar-10 dataset if present
floyd_cifar10_location = '/cifar/cifar-10-python.tar.gz'
if isfile(floyd_cifar10_location):
    tar_gz_path = floyd_cifar10_location
else:
    tar_gz_path = 'cifar-10-python.tar.gz'
class DLProgress(tqdm):
    last_block = 0
    def hook(self, block_num=1, block_size=1, total_size=None):
        self.total = total_size
        self.update((block_num - self.last_block) * block_size)
        self.last_block = block_num
if not isfile(tar_gz_path):
    with DLProgress(unit='B', unit_scale=True, miniters=1, desc='CIFAR-10 Dataset') as pbar:
        urlretrieve(
            'https://www.cs.toronto.edu/~kriz/cifar-10-python.tar.gz',
            tar_gz_path,
            pbar.hook)
if not isdir(cifar10_dataset_folder_path):
    with tarfile.open(tar_gz_path) as tar:
        tar.extractall()
        tar.close()
tests.test_folder_path(cifar10_dataset_folder_path)
Explanation: Image Classification
In this project, you'll classify images from the CIFAR-10 dataset.  The dataset consists of airplanes, dogs, cats, and other objects. You'll preprocess the images, then train a convolutional neural network on all the samples. The images need to be normalized and the labels need to be one-hot encoded.  You'll get to apply what you learned and build a convolutional, max pooling, dropout, and fully connected layers.  At the end, you'll get to see your neural network's predictions on the sample images.
Get the Data
Run the following cell to download the CIFAR-10 dataset for python.
End of explanation
%matplotlib inline
%config InlineBackend.figure_format = 'retina'
import helper
import numpy as np
# Explore the dataset
batch_id = 2
sample_id = 15
helper.display_stats(cifar10_dataset_folder_path, batch_id, sample_id)
Explanation: Explore the Data
The dataset is broken into batches to prevent your machine from running out of memory.  The CIFAR-10 dataset consists of 5 batches, named data_batch_1, data_batch_2, etc.. Each batch contains the labels and images that are one of the following:
* airplane
* automobile
* bird
* cat
* deer
* dog
* frog
* horse
* ship
* truck
Understanding a dataset is part of making predictions on the data.  Play around with the code cell below by changing the batch_id and sample_id. The batch_id is the id for a batch (1-5). The sample_id is the id for a image and label pair in the batch.
Ask yourself "What are all possible labels?", "What is the range of values for the image data?", "Are the labels in order or random?".  Answers to questions like these will help you preprocess the data and end up with better predictions.
End of explanation
import numpy
def normalize(x):
    
    Normalize a list of sample image data in the range of 0 to 1
    : x: List of image data.  The image shape is (32, 32, 3)
    : return: Numpy array of normalize data
    
    # TODO: Implement Function
    x = numpy.array(x)
    x_normed = (x - x.min(0)) / x.ptp(0)
    return x_normed
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
tests.test_normalize(normalize)
Explanation: Implement Preprocess Functions
Normalize
In the cell below, implement the normalize function to take in image data, x, and return it as a normalized Numpy array. The values should be in the range of 0 to 1, inclusive.  The return object should be the same shape as x.
End of explanation
def one_hot_encode(x):
    
    One hot encode a list of sample labels. Return a one-hot encoded vector for each label.
    : x: List of sample Labels
    : return: Numpy array of one-hot encoded labels
    
    nb_classes = 10
    targets = numpy.array(x).reshape(-1)
    one_hot_targets = numpy.eye(nb_classes)[targets]
    return one_hot_targets
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
tests.test_one_hot_encode(one_hot_encode)
Explanation: One-hot encode
Just like the previous code cell, you'll be implementing a function for preprocessing.  This time, you'll implement the one_hot_encode function. The input, x, are a list of labels.  Implement the function to return the list of labels as One-Hot encoded Numpy array.  The possible values for labels are 0 to 9. The one-hot encoding function should return the same encoding for each value between each call to one_hot_encode.  Make sure to save the map of encodings outside the function.
Hint: Don't reinvent the wheel.
End of explanation
DON'T MODIFY ANYTHING IN THIS CELL
# Preprocess Training, Validation, and Testing Data
helper.preprocess_and_save_data(cifar10_dataset_folder_path, normalize, one_hot_encode)
Explanation: Randomize Data
As you saw from exploring the data above, the order of the samples are randomized.  It doesn't hurt to randomize it again, but you don't need to for this dataset.
Preprocess all the data and save it
Running the code cell below will preprocess all the CIFAR-10 data and save it to file. The code below also uses 10% of the training data for validation.
End of explanation
DON'T MODIFY ANYTHING IN THIS CELL
import pickle
import problem_unittests as tests
import helper
# Load the Preprocessed Validation data
valid_features, valid_labels = pickle.load(open('preprocess_validation.p', mode='rb'))
Explanation: Check Point
This is your first checkpoint.  If you ever decide to come back to this notebook or have to restart the notebook, you can start from here.  The preprocessed data has been saved to disk.
End of explanation
import tensorflow as tf
def neural_net_image_input(image_shape):
    
    Return a Tensor for a batch of image input
    : image_shape: Shape of the images
    : return: Tensor for image input.
    
    return tf.placeholder(tf.float32, shape=(None, image_shape[0], 
                                             image_shape[1], image_shape[2]), name="x")
def neural_net_label_input(n_classes):
    
    Return a Tensor for a batch of label input
    : n_classes: Number of classes
    : return: Tensor for label input.
    
    return tf.placeholder(tf.float32, shape=(None, n_classes), name="y")
def neural_net_keep_prob_input():
    
    Return a Tensor for keep probability
    : return: Tensor for keep probability.
    
    # TODO: Implement Function
    return tf.placeholder(tf.float32, name="keep_prob")
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
tf.reset_default_graph()
tests.test_nn_image_inputs(neural_net_image_input)
tests.test_nn_label_inputs(neural_net_label_input)
tests.test_nn_keep_prob_inputs(neural_net_keep_prob_input)
Explanation: Build the network
For the neural network, you'll build each layer into a function.  Most of the code you've seen has been outside of functions. To test your code more thoroughly, we require that you put each layer in a function.  This allows us to give you better feedback and test for simple mistakes using our unittests before you submit your project.
Note: If you're finding it hard to dedicate enough time for this course each week, we've provided a small shortcut to this part of the project. In the next couple of problems, you'll have the option to use classes from the TensorFlow Layers or TensorFlow Layers (contrib) packages to build each layer, except the layers you build in the "Convolutional and Max Pooling Layer" section.  TF Layers is similar to Keras's and TFLearn's abstraction to layers, so it's easy to pickup.
However, if you would like to get the most out of this course, try to solve all the problems without using anything from the TF Layers packages. You can still use classes from other packages that happen to have the same name as ones you find in TF Layers! For example, instead of using the TF Layers version of the conv2d class, tf.layers.conv2d, you would want to use the TF Neural Network version of conv2d, tf.nn.conv2d. 
Let's begin!
Input
The neural network needs to read the image data, one-hot encoded labels, and dropout keep probability. Implement the following functions
* Implement neural_net_image_input
 * Return a TF Placeholder
 * Set the shape using image_shape with batch size set to None.
 * Name the TensorFlow placeholder "x" using the TensorFlow name parameter in the TF Placeholder.
* Implement neural_net_label_input
 * Return a TF Placeholder
 * Set the shape using n_classes with batch size set to None.
 * Name the TensorFlow placeholder "y" using the TensorFlow name parameter in the TF Placeholder.
* Implement neural_net_keep_prob_input
 * Return a TF Placeholder for dropout keep probability.
 * Name the TensorFlow placeholder "keep_prob" using the TensorFlow name parameter in the TF Placeholder.
These names will be used at the end of the project to load your saved model.
Note: None for shapes in TensorFlow allow for a dynamic size.
End of explanation
def conv2d_maxpool(x_tensor, conv_num_outputs, conv_ksize, conv_strides, pool_ksize, pool_strides):
    
    Apply convolution then max pooling to x_tensor
    :param x_tensor: TensorFlow Tensor
    :param conv_num_outputs: Number of outputs for the convolutional layer
    :param conv_ksize: kernal size 2-D Tuple for the convolutional layer
    :param conv_strides: Stride 2-D Tuple for convolution
    :param pool_ksize: kernal size 2-D Tuple for pool
    :param pool_strides: Stride 2-D Tuple for pool
    : return: A tensor that represents convolution and max pooling of x_tensor
    
    batch_size, in_width, in_height, in_depth = x_tensor.get_shape().as_list()
    weights = tf.Variable(tf.truncated_normal([conv_ksize[0], conv_ksize[1], 
                                               in_depth, conv_num_outputs]))
    biases = tf.Variable(tf.zeros(conv_num_outputs))
    
    conv = tf.nn.conv2d(x_tensor, weights, strides=[1, conv_strides[0], conv_strides[1], 1],
                        padding='SAME')
    conv = tf.nn.bias_add(conv, biases)
    conv = tf.nn.relu(conv)
    
    filter_shape = [1, pool_ksize[0], pool_ksize[1], 1]
    strides = [1, pool_strides[0], pool_strides[1], 1]
    return tf.nn.max_pool(conv, filter_shape, strides, 'SAME')
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
tests.test_con_pool(conv2d_maxpool)
Explanation: Convolution and Max Pooling Layer
Convolution layers have a lot of success with images. For this code cell, you should implement the function conv2d_maxpool to apply convolution then max pooling:
* Create the weight and bias using conv_ksize, conv_num_outputs and the shape of x_tensor.
* Apply a convolution to x_tensor using weight and conv_strides.
 * We recommend you use same padding, but you're welcome to use any padding.
* Add bias
* Add a nonlinear activation to the convolution.
* Apply Max Pooling using pool_ksize and pool_strides.
 * We recommend you use same padding, but you're welcome to use any padding.
Note: You can't use TensorFlow Layers or TensorFlow Layers (contrib) for this layer, but you can still use TensorFlow's Neural Network package. You may still use the shortcut option for all the other layers.
End of explanation
def flatten(x_tensor):
    
    Flatten x_tensor to (Batch Size, Flattened Image Size)
    : x_tensor: A tensor of size (Batch Size, ...), where ... are the image dimensions.
    : return: A tensor of size (Batch Size, Flattened Image Size).
    
    # TODO: Implement Function
    return tf.contrib.layers.flatten(x_tensor)
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tests.test_flatten(flatten)
Explanation: Flatten Layer
Implement the flatten function to change the dimension of x_tensor from a 4-D tensor to a 2-D tensor.  The output should be the shape (Batch Size, Flattened Image Size). Shortcut option: you can use classes from the TensorFlow Layers or TensorFlow Layers (contrib) packages for this layer. For more of a challenge, only use other TensorFlow packages.
End of explanation
def fully_conn(x_tensor, num_outputs):
    
    Apply a fully connected layer to x_tensor using weight and bias
    : x_tensor: A 2-D tensor where the first dimension is batch size.
    : num_outputs: The number of output that the new tensor should be.
    : return: A 2-D tensor where the second dimension is num_outputs.
    
    # TODO: Implement Function
    return tf.contrib.layers.fully_connected(x_tensor, num_outputs)
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tests.test_fully_conn(fully_conn)
Explanation: Fully-Connected Layer
Implement the fully_conn function to apply a fully connected layer to x_tensor with the shape (Batch Size, num_outputs). Shortcut option: you can use classes from the TensorFlow Layers or TensorFlow Layers (contrib) packages for this layer. For more of a challenge, only use other TensorFlow packages.
End of explanation
def output(x_tensor, num_outputs):
    
    Apply a output layer to x_tensor using weight and bias
    : x_tensor: A 2-D tensor where the first dimension is batch size.
    : num_outputs: The number of output that the new tensor should be.
    : return: A 2-D tensor where the second dimension is num_outputs.
    
    # TODO: Implement Function
    return tf.contrib.layers.fully_connected(x_tensor, num_outputs)
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tests.test_output(output)
Explanation: Output Layer
Implement the output function to apply a fully connected layer to x_tensor with the shape (Batch Size, num_outputs). Shortcut option: you can use classes from the TensorFlow Layers or TensorFlow Layers (contrib) packages for this layer. For more of a challenge, only use other TensorFlow packages.
Note: Activation, softmax, or cross entropy should not be applied to this.
End of explanation
def conv_net(x, keep_prob):
    
    Create a convolutional neural network model
    : x: Placeholder tensor that holds image data.
    : keep_prob: Placeholder tensor that hold dropout keep probability.
    : return: Tensor that represents logits
    
    # TODO: Apply 1, 2, or 3 Convolution and Max Pool layers
    #    Play around with different number of outputs, kernel size and stride
    # Function Definition from Above:
    #    conv2d_maxpool(x_tensor, conv_num_outputs, conv_ksize, conv_strides, pool_ksize, pool_strides)
    conv_ksize = [2,2]
    conv_strides = [1,1]
    pool_ksize = [2,2]
    pool_strides = [1,1]
    conv_num_outputs = 16
    x_tensor = conv2d_maxpool(x, conv_num_outputs, conv_ksize, conv_strides, pool_ksize, pool_strides)
    x_tensor = tf.nn.dropout(x_tensor, keep_prob)
    
    conv_ksize = [3,3]
    conv_strides = [2,2]
    pool_ksize = [2,2]
    pool_strides = [2,2]
    
    conv_num_outputs = 40
    x_tensor = conv2d_maxpool(x, conv_num_outputs, conv_ksize, conv_strides, pool_ksize, pool_strides)
    x_tensor = tf.nn.dropout(x_tensor, keep_prob)
    
    conv_num_outputs = 10
    x_tensor = conv2d_maxpool(x, conv_num_outputs, conv_ksize, conv_strides, pool_ksize, pool_strides)
    x_tensor = tf.nn.dropout(x_tensor, keep_prob)
    # TODO: Apply a Flatten Layer
    # Function Definition from Above:
    #   flatten(x_tensor)
    x_tensor = flatten(x_tensor)
    # TODO: Apply 1, 2, or 3 Fully Connected Layers
    #    Play around with different number of outputs
    num_outputs = 60
    x_tensor = fully_conn(x_tensor, num_outputs)
    num_outputs = 40
    x_tensor = fully_conn(x_tensor, num_outputs)
    num_outputs = 20
    x_tensor = fully_conn(x_tensor, num_outputs)
    num_classes = 10
    return output(x_tensor, num_classes)
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##############################
## Build the Neural Network ##
##############################
# Remove previous weights, bias, inputs, etc..
tf.reset_default_graph()
# Inputs
x = neural_net_image_input((32, 32, 3))
y = neural_net_label_input(10)
keep_prob = neural_net_keep_prob_input()
# Model
logits = conv_net(x, keep_prob)
# Name logits Tensor, so that is can be loaded from disk after training
logits = tf.identity(logits, name='logits')
# Loss and Optimizer
cost = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits=logits, labels=y))
optimizer = tf.train.AdamOptimizer().minimize(cost)
# Accuracy
correct_pred = tf.equal(tf.argmax(logits, 1), tf.argmax(y, 1))
accuracy = tf.reduce_mean(tf.cast(correct_pred, tf.float32), name='accuracy')
tests.test_conv_net(conv_net)
Explanation: Create Convolutional Model
Implement the function conv_net to create a convolutional neural network model. The function takes in a batch of images, x, and outputs logits.  Use the layers you created above to create this model:
Apply 1, 2, or 3 Convolution and Max Pool layers
Apply a Flatten Layer
Apply 1, 2, or 3 Fully Connected Layers
Apply an Output Layer
Return the output
Apply TensorFlow's Dropout to one or more layers in the model using keep_prob.
End of explanation
def train_neural_network(session, optimizer, keep_probability, feature_batch, label_batch):
    
    Optimize the session on a batch of images and labels
    : session: Current TensorFlow session
    : optimizer: TensorFlow optimizer function
    : keep_probability: keep probability
    : feature_batch: Batch of Numpy image data
    : label_batch: Batch of Numpy label data
    
    session.run(optimizer, feed_dict={x: feature_batch, y: label_batch, keep_prob: keep_probability})
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tests.test_train_nn(train_neural_network)
Explanation: Train the Neural Network
Single Optimization
Implement the function train_neural_network to do a single optimization.  The optimization should use optimizer to optimize in session with a feed_dict of the following:
* x for image input
* y for labels
* keep_prob for keep probability for dropout
This function will be called for each batch, so tf.global_variables_initializer() has already been called.
Note: Nothing needs to be returned. This function is only optimizing the neural network.
End of explanation
def print_stats(session, feature_batch, label_batch, cost, accuracy):
    
    Print information about loss and validation accuracy
    : session: Current TensorFlow session
    : feature_batch: Batch of Numpy image data
    : label_batch: Batch of Numpy label data
    : cost: TensorFlow cost function
    : accuracy: TensorFlow accuracy function
    
    # TODO: Implement Function
    cost = session.run(cost, feed_dict={x: feature_batch, y: label_batch, keep_prob: keep_probability})
    acc = session.run(accuracy, feed_dict={x: feature_batch, y: label_batch, keep_prob: keep_probability})
    validation_accuracy = session.run(accuracy, feed_dict={x: valid_features, y: valid_labels, keep_prob: 1.0})
    print('cost: {}'.format(cost))
    print('accuracy: {}'.format(accuracy))    
    print('validation accuracy: {}'.format(validation_accuracy))    
Explanation: Show Stats
Implement the function print_stats to print loss and validation accuracy.  Use the global variables valid_features and valid_labels to calculate validation accuracy.  Use a keep probability of 1.0 to calculate the loss and validation accuracy.
End of explanation
# TODO: Tune Parameters
epochs = 70
batch_size = 256
keep_probability = 0.9
Explanation: Hyperparameters
Tune the following parameters:
* Set epochs to the number of iterations until the network stops learning or start overfitting
* Set batch_size to the highest number that your machine has memory for.  Most people set them to common sizes of memory:
 * 64
 * 128
 * 256
 * ...
* Set keep_probability to the probability of keeping a node using dropout
End of explanation
DON'T MODIFY ANYTHING IN THIS CELL
print('Checking the Training on a Single Batch...')
with tf.Session() as sess:
    # Initializing the variables
    sess.run(tf.global_variables_initializer())
    
    # Training cycle
    for epoch in range(epochs):
        batch_i = 1
        for batch_features, batch_labels in helper.load_preprocess_training_batch(batch_i, batch_size):
            train_neural_network(sess, optimizer, keep_probability, batch_features, batch_labels)
        print('Epoch {:>2}, CIFAR-10 Batch {}:  '.format(epoch + 1, batch_i), end='')
        print_stats(sess, batch_features, batch_labels, cost, accuracy)
Explanation: Train on a Single CIFAR-10 Batch
Instead of training the neural network on all the CIFAR-10 batches of data, let's use a single batch. This should save time while you iterate on the model to get a better accuracy.  Once the final validation accuracy is 50% or greater, run the model on all the data in the next section.
End of explanation
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save_model_path = './image_classification'
print('Training...')
with tf.Session() as sess:
    # Initializing the variables
    sess.run(tf.global_variables_initializer())
    
    # Training cycle
    for epoch in range(epochs):
        # Loop over all batches
        n_batches = 5
        for batch_i in range(1, n_batches + 1):
            for batch_features, batch_labels in helper.load_preprocess_training_batch(batch_i, batch_size):
                train_neural_network(sess, optimizer, keep_probability, batch_features, batch_labels)
            print('Epoch {:>2}, CIFAR-10 Batch {}:  '.format(epoch + 1, batch_i), end='')
            print_stats(sess, batch_features, batch_labels, cost, accuracy)
            
    # Save Model
    saver = tf.train.Saver()
    save_path = saver.save(sess, save_model_path)
Explanation: Fully Train the Model
Now that you got a good accuracy with a single CIFAR-10 batch, try it with all five batches.
End of explanation
DON'T MODIFY ANYTHING IN THIS CELL
%matplotlib inline
%config InlineBackend.figure_format = 'retina'
import tensorflow as tf
import pickle
import helper
import random
# Set batch size if not already set
try:
    if batch_size:
        pass
except NameError:
    batch_size = 64
save_model_path = './image_classification'
n_samples = 4
top_n_predictions = 3
def test_model():
    
    Test the saved model against the test dataset
    
    test_features, test_labels = pickle.load(open('preprocess_test.p', mode='rb'))
    loaded_graph = tf.Graph()
    with tf.Session(graph=loaded_graph) as sess:
        # Load model
        loader = tf.train.import_meta_graph(save_model_path + '.meta')
        loader.restore(sess, save_model_path)
        # Get Tensors from loaded model
        loaded_x = loaded_graph.get_tensor_by_name('x:0')
        loaded_y = loaded_graph.get_tensor_by_name('y:0')
        loaded_keep_prob = loaded_graph.get_tensor_by_name('keep_prob:0')
        loaded_logits = loaded_graph.get_tensor_by_name('logits:0')
        loaded_acc = loaded_graph.get_tensor_by_name('accuracy:0')
        
        # Get accuracy in batches for memory limitations
        test_batch_acc_total = 0
        test_batch_count = 0
        
        for test_feature_batch, test_label_batch in helper.batch_features_labels(test_features, test_labels, batch_size):
            test_batch_acc_total += sess.run(
                loaded_acc,
                feed_dict={loaded_x: test_feature_batch, loaded_y: test_label_batch, loaded_keep_prob: 1.0})
            test_batch_count += 1
        print('Testing Accuracy: {}\n'.format(test_batch_acc_total/test_batch_count))
        # Print Random Samples
        random_test_features, random_test_labels = tuple(zip(*random.sample(list(zip(test_features, test_labels)), n_samples)))
        random_test_predictions = sess.run(
            tf.nn.top_k(tf.nn.softmax(loaded_logits), top_n_predictions),
            feed_dict={loaded_x: random_test_features, loaded_y: random_test_labels, loaded_keep_prob: 1.0})
        helper.display_image_predictions(random_test_features, random_test_labels, random_test_predictions)
test_model()
Explanation: Checkpoint
The model has been saved to disk.
Test Model
Test your model against the test dataset.  This will be your final accuracy. You should have an accuracy greater than 50%. If you don't, keep tweaking the model architecture and parameters.
End of explanation
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