mnist_irnn.py

'''This is a reproduction of the IRNN experiment
with pixel-by-pixel sequential MNIST in
"A Simple Way to Initialize Recurrent Networks of Rectified Linear Units"
by Quoc V. Le, Navdeep Jaitly, Geoffrey E. Hinton

arxiv:1504.00941v2 [cs.NE] 7 Apr 2015
http://arxiv.org/pdf/1504.00941v2.pdf

Optimizer is replaced with RMSprop which yields more stable and steady
improvement.

Reaches 0.93 train/test accuracy after 900 epochs
(which roughly corresponds to 1687500 steps in the original paper.)
'''

from __future__ import print_function

import keras
from keras.datasets import mnist
from keras.models import Sequential
from keras.layers import Dense, Activation
from keras.layers import SimpleRNN
from keras import initializers
from keras.optimizers import RMSprop
import os
from keras import backend as K
import numpy as np
import tensorflow as tf
import logging

batch_size = 32
num_classes = 10
epochs = 200
hidden_units = 100

learning_rate = 1e-6
clip_norm = 1.0

model_name = 'IRNN'
if not os.path.exists(os.path.join('expr', model_name)):
    os.system('mkdir {}'.format(os.path.join('expr', model_name)))

# the data, shuffled and split between train and test sets
(x_train, y_train), (x_test, y_test) = mnist.load_data()

x_train = x_train.reshape(x_train.shape[0], -1, 1)
x_test = x_test.reshape(x_test.shape[0], -1, 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)

print('Evaluate Model {}...'.format(model_name))
model = Sequential()
model.add(SimpleRNN(hidden_units,
                    kernel_initializer=initializers.RandomNormal(stddev=0.001),
                    recurrent_initializer=initializers.Identity(gain=1.0),
                    activation='relu',
                    input_shape=x_train.shape[1:]))
model.add(Dense(num_classes))
model.add(Activation('softmax'))
rmsprop = RMSprop(lr=learning_rate)
model.compile(loss='categorical_crossentropy',
              optimizer=rmsprop,
              metrics=['accuracy'])

train_log = keras.callbacks.CSVLogger(os.path.join('expr', model_name, 'training.log'))

class ParamLogger(keras.callbacks.Callback):
    def on_train_begin(self, logs={}):
        logging.basicConfig(filename=os.path.join('expr', model_name,  'params_recorder.log'), level=logging.INFO)

    def on_batch_end(self, batch, logs={}):
        return

    def on_train_end(self, logs={}):
        recurrent_weights = model.layers[0].get_weights()[1]
        eigenvalue, _ = np.linalg.eig(recurrent_weights)
        np.savez(os.path.join('expr', model_name, "RecurrentKernel-final-epoch.npy"), kernel=recurrent_weights, eigenvalue=eigenvalue)
        return

    def on_epoch_begin(self, epoch, logs={}):
        # print('Params: {} | {}'.format(model.layers[0].trainable_weights[1], model.layers[0].get_weights()[1]))
        return

    def on_epoch_end(self, epoch, logs={}):
        logging.info('Epoch: {}'.format(epoch))
        logging.info('Eigenvalue of {}'.format(model.layers[0].trainable_weights[1]))
        recurrent_weights = model.layers[0].get_weights()[1]
        eigenvalue, _ = np.linalg.eig(recurrent_weights)
        logging.info('EigenValue | Max: {} | Min: {}'.format(np.max(eigenvalue), np.min(eigenvalue)))
        logging.info('{}\n\n'.format(eigenvalue))
        if epoch % 5 == 0:
            np.savez(os.path.join('expr', model_name, "RecurrentKernel-epoch-{}.npy".format(epoch)), kernel=recurrent_weights, eigenvalue=eigenvalue)
        return

    def on_batch_begin(self, batch, logs={}):
        return

    def on_batch_end(self, batch, logs={}):
        return

paramlogger = ParamLogger()

ckpt_saver = keras.callbacks.ModelCheckpoint(os.path.join('expr', model_name, 'weights.{epoch:02d}-{acc: .4f}.hdf5'), 
        monitor='acc', 
        verbose=1, 
        period=10)

model.fit(x_train, y_train,
          batch_size=batch_size,
          epochs=epochs,
          verbose=1,
          validation_data=(x_test, y_test),
          callbacks=[train_log, ckpt_saver, paramlogger])

scores = model.evaluate(x_test, y_test, verbose=0)
print('Model {} test score: {}'.format(model_name, scores[0]))
print('Model {} test accuracy: {}'.format(model_name, scores[1]))