Machine Learning Foundations: Exercise 2 Handwriting digit model with 99% accuracy

Exercise 2: Handwriting digit model with 99% accuracy:code lab link

Write an MNIST classifier that trains to 99% accuracy or above, and does it without a fixed number of epochs -- i.e. you should stop training once you reach that level of accuracy.

Code:

	import tensorflow as tf
	# Callback function to check model accuracy
	class RayCallback(tf.keras.callbacks.Callback):
	def on_epoch_end(self, epoch, logs={}):
	if(logs.get('accuracy')>0.99):
	print("\nReached 99% accuracy so cancelling training!")
	self.model.stop_training = True
	# Load the MNIST handwrite digit data set
	mnist = tf.keras.datasets.mnist
	(x_train, y_train),(x_test, y_test) = mnist.load_data()
	# Normalize training data and callback function
	callbacks = RayCallback()
	x_train = x_train/255.0
	x_test = x_test/255.0
	# Create an 3 layer model: Flatten -> 128 input -> 10 output
	model = tf.keras.models.Sequential([
	tf.keras.layers.Flatten(),
	tf.keras.layers.Dense(128, activation=tf.nn.relu),
	tf.keras.layers.Dense(10, activation=tf.nn.softmax)
	])
	# Setting optimizer and loss function
	model.compile(optimizer='adam',
	loss='sparse_categorical_crossentropy',
	metrics=['accuracy'])
	# Training model untill accuracy > 99%
	model.fit(x_train, y_train, epochs=15, callbacks=[callbacks])
	# Evaluate with test data
	model.evaluate(x_test, y_test)

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Result:

	Epoch 1/15
	1875/1875 [==============================] - 3s 2ms/step - loss: 0.2570 - accuracy: 0.9265
	Epoch 2/15
	1875/1875 [==============================] - 4s 2ms/step - loss: 0.1133 - accuracy: 0.9667
	Epoch 3/15
	1875/1875 [==============================] - 3s 2ms/step - loss: 0.0778 - accuracy: 0.9765
	Epoch 4/15
	1875/1875 [==============================] - 3s 2ms/step - loss: 0.0580 - accuracy: 0.9822
	Epoch 5/15
	1875/1875 [==============================] - 3s 2ms/step - loss: 0.0444 - accuracy: 0.9859
	Epoch 6/15
	1875/1875 [==============================] - 3s 2ms/step - loss: 0.0345 - accuracy: 0.9893
	Epoch 7/15
	1863/1875 [============================>.] - ETA: 0s - loss: 0.0268 - accuracy: 0.9916
	Reached 99% accuracy so cancelling training!
	1875/1875 [==============================] - 3s 2ms/step - loss: 0.0271 - accuracy: 0.9916
	313/313 [==============================] - 0s 1ms/step - loss: 0.0843 - accuracy: 0.9774
	[0.08431357890367508, 0.977400004863739]

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