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from keras.datasets import cifar10 # subroutines for fetching the CIFAR-10 dataset
from keras.models import Model # basic class for specifying and training a neural network
from keras.layers import Input, Convolution2D, MaxPooling2D, Dense, Dropout, Flatten
from keras.utils import np_utils # utilities for one-hot encoding of ground truth values
import numpy as np
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from matplotlib import pyplot
from scipy.misc import toimage
# load data
(X_train, y_train), (X_test, y_test) = cifar10.load_data()
# create a grid of 3x3 images
for i in range(0, 9):
pyplot.subplot(330 + 1 + i)
pyplot.imshow(toimage(X_train[i]))
# show the plot
pyplot.show()
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print(X_train.shape)
print(X_test.shape)
print(np.unique(y_train).shape[0])
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num_train, height, width, depth = X_train.shape # there are 50000 training examples in CIFAR-10
num_test = X_test.shape[0] # there are 10000 test examples in CIFAR-10
num_classes = np.unique(y_train).shape[0] # there are 10 image classes
X_train = X_train.astype('float32')
X_test = X_test.astype('float32')
X_train /= np.max(X_train) # Normalise data to [0, 1] range
X_test /= np.max(X_test) # Normalise data to [0, 1] range
Y_train = np_utils.to_categorical(y_train, num_classes) # One-hot encode the labels
Y_test = np_utils.to_categorical(y_test, num_classes) # One-hot encode the labels
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batch_size = 32 # in each iteration, we consider 32 training examples at once
num_epochs = 2 ## 200 # we iterate 200 times over the entire training set
## just to exp in my local systtem, I set num_epochs to 2
kernel_size = 3 # we will use 3x3 kernels throughout
pool_size = 2 # we will use 2x2 pooling throughout
conv_depth_1 = 32 # we will initially have 32 kernels per conv. layer...
conv_depth_2 = 64 # ...switching to 64 after the first pooling layer
drop_prob_1 = 0.25 # dropout after pooling with probability 0.25
drop_prob_2 = 0.5 # dropout in the FC layer with probability 0.5
hidden_size = 512 # the FC layer will have 512 neurons
def build_model2():
inp = Input(shape=(height, width, depth)) # depth goes last in TensorFlow back-end (first in Theano)
# Conv [32] -> Conv [32] -> Pool (with dropout on the pooling layer)
conv_1 = Convolution2D(conv_depth_1, (kernel_size, kernel_size), padding='same', activation='relu')(inp)
conv_2 = Convolution2D(conv_depth_1, (kernel_size, kernel_size), padding='same', activation='relu')(conv_1)
pool_1 = MaxPooling2D(pool_size=(pool_size, pool_size))(conv_2)
drop_1 = Dropout(drop_prob_1)(pool_1)
# Conv [64] -> Conv [64] -> Pool (with dropout on the pooling layer)
conv_3 = Convolution2D(conv_depth_2, (kernel_size, kernel_size), padding='same', activation='relu')(drop_1)
conv_4 = Convolution2D(conv_depth_2, (kernel_size, kernel_size), padding='same', activation='relu')(conv_3)
pool_2 = MaxPooling2D(pool_size=(pool_size, pool_size))(conv_4)
drop_2 = Dropout(drop_prob_1)(pool_2)
# Now flatten to 1D, apply FC -> ReLU (with dropout) -> softmax
flat = Flatten()(drop_2)
hidden = Dense(hidden_size, activation='relu')(flat)
drop_3 = Dropout(drop_prob_2)(hidden)
out = Dense(num_classes, activation='softmax')(drop_3)
model = Model(inputs=inp, outputs=out) # To define a model, just specify its input and output layers
model.compile(loss='categorical_crossentropy', # using the cross-entropy loss function
optimizer='adam', # using the Adam optimiser
metrics=['accuracy']) # reporting the accuracy
return model
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history = build_model2().fit(X_train, Y_train, # Train the model using the training set...
batch_size=batch_size, epochs=num_epochs,
verbose=1, validation_split=0.1) # ...holding out 10% of the data for validation
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build_model2().evaluate(X_test, Y_test, verbose=1) # Evaluate the trained model on the test set!
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