'''Trains a simple convnet on the MNIST dataset. | |
Gets to 99.25% test accuracy after 12 epochs | |
(there is still a lot of margin for parameter tuning). | |
16 seconds per epoch on a GRID K520 GPU. | |
''' | |
from __future__ import print_function | |
import keras | |
from keras.datasets import mnist | |
from keras.models import Sequential | |
from keras.layers import Dense, Dropout, Flatten | |
from keras.layers import Conv2D, MaxPooling2D | |
from keras import backend as K | |
batch_size = 128 | |
num_classes = 10 | |
epochs = 12 | |
# input image dimensions | |
img_rows, img_cols = 28, 28 | |
# the data, split between train and test sets | |
(x_train, y_train), (x_test, y_test) = mnist.load_data() | |
if K.image_data_format() == 'channels_first': | |
x_train = x_train.reshape(x_train.shape[0], 1, img_rows, img_cols) | |
x_test = x_test.reshape(x_test.shape[0], 1, img_rows, img_cols) | |
input_shape = (1, img_rows, img_cols) | |
else: | |
x_train = x_train.reshape(x_train.shape[0], img_rows, img_cols, 1) | |
x_test = x_test.reshape(x_test.shape[0], img_rows, img_cols, 1) | |
input_shape = (img_rows, img_cols, 1) | |
x_train = x_train.astype('float32') | |
x_test = x_test.astype('float32') | |
x_train /= 255 | |
x_test /= 255 | |
print('x_train shape:', x_train.shape) | |
print(x_train.shape[0], 'train samples') | |
print(x_test.shape[0], 'test samples') | |
# convert class vectors to binary class matrices | |
y_train = keras.utils.to_categorical(y_train, num_classes) | |
y_test = keras.utils.to_categorical(y_test, num_classes) | |
model = Sequential() | |
model.add(Conv2D(32, kernel_size=(3, 3), | |
activation='relu', | |
input_shape=input_shape)) | |
model.add(Conv2D(64, (3, 3), activation='relu')) | |
model.add(MaxPooling2D(pool_size=(2, 2))) | |
model.add(Dropout(0.25)) | |
model.add(Flatten()) | |
model.add(Dense(128, activation='relu')) | |
model.add(Dropout(0.5)) | |
model.add(Dense(num_classes, activation='softmax')) | |
model.compile(loss=keras.losses.categorical_crossentropy, | |
optimizer=keras.optimizers.Adadelta(), | |
metrics=['accuracy']) | |
model.fit(x_train, y_train, | |
batch_size=batch_size, | |
epochs=epochs, | |
verbose=1, | |
validation_data=(x_test, y_test)) | |
score = model.evaluate(x_test, y_test, verbose=0) | |
print('Test loss:', score[0]) | |
print('Test accuracy:', score[1]) |
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