def fit_predict(data, labels, action, filename, test_datasets = [], learning_rate=0.1, n_epochs=20, nkerns=[20, 50], batch_size=500, seed=8000):
rng = numpy.random.RandomState(seed)
x = T.matrix('x') # the data is presented as rasterized images
y = T.ivector('y') # the labels are presented as 1D vector of [int] labels
index = T.lscalar() # index to a [mini]batch
if action=='fit':
NUM_TRAIN = len(data)
if NUM_TRAIN % batch_size != 0: #if the last batch is not full, just don't use the remainder
whole = (NUM_TRAIN / batch_size) * batch_size
data = data[:whole]
NUM_TRAIN = len(data)
# random permutation
indices = rng.permutation(NUM_TRAIN)
data, labels = data[indices, :], labels[indices]
# batch_size == 500, splits (480, 20). We will use 96% of the data for training, and the rest to validate the NN while training
is_train = numpy.array( ([0]* (batch_size - 20) + [1] * 20) * (NUM_TRAIN / batch_size))
# now we split the dataset to test and valid datasets
train_set_x, train_set_y = numpy.array(data[is_train==0]), labels[is_train==0]
valid_set_x, valid_set_y = numpy.array(data[is_train==1]), labels[is_train==1]
# compute number of minibatches
n_train_batches = len(train_set_y) / batch_size
n_valid_batches = len(valid_set_y) / batch_size
######################
# BUILD ACTUAL MODEL #
######################
print '... building the model'
# allocate symbolic variables for the data
epoch = T.scalar()
#index = T.lscalar() # index to a [mini]batch
#x = T.matrix('x') # the data is presented as rasterized images
#y = T.ivector('y') # the labels are presented as 1D vector of [int] labels
# construct the CNN class
classifier = CNN(
rng=rng,
input=x,
nkerns = nkerns,
batch_size = batch_size
)
train_set_x = theano.shared(numpy.asarray(train_set_x, dtype=theano.config.floatX))
train_set_y = T.cast(theano.shared(numpy.asarray(train_set_y, dtype=theano.config.floatX)), 'int32')
valid_set_x = theano.shared(numpy.asarray(valid_set_x, dtype=theano.config.floatX))
valid_set_y = T.cast(theano.shared(numpy.asarray(valid_set_y, dtype=theano.config.floatX)), 'int32')
validate_model = theano.function(
inputs=[index],
outputs=classifier.errors(y),
givens={
x: valid_set_x[index * batch_size:(index + 1) * batch_size],
y: valid_set_y[index * batch_size:(index + 1) * batch_size]
}
)
cost = classifier.layer3.negative_log_likelihood(y)
# create a list of gradients for all model parameters
grads = T.grad(cost, classifier.params)
# specify how to update the parameters of the model as a list of (variable, update expression) pairs
updates = [
(param_i, param_i - learning_rate * grad_i)
for param_i, grad_i in zip(classifier.params, grads)
]
# compiling a Theano function `train_model` that returns the cost, but
# in the same time updates the parameter of the model based on the rules defined in `updates`
train_model = theano.function(
inputs=[index],
outputs=cost,
updates=updates,
givens={
x: train_set_x[index * batch_size: (index + 1) * batch_size],
y: train_set_y[index * batch_size: (index + 1) * batch_size]
}
)
###############
# TRAIN MODEL #
###############
print '... training'
best_iter = 0
test_score = 0.
start_time = time.clock()
epoch = 0
# here is an example how to print the current value of a Theano variable: print test_set_x.shape.eval()
# start training
while (epoch < n_epochs):
epoch = epoch + 1
for minibatch_index in xrange(n_train_batches):
minibatch_avg_cost = train_model(minibatch_index)
iter = (epoch - 1) * n_train_batches + minibatch_index
if (epoch) % 5 == 0 and minibatch_index==0:
# compute zero-one loss on validation set
validation_losses = [validate_model(i) for i
in xrange(n_valid_batches)]
this_validation_loss = numpy.mean(validation_losses)
print(
'epoch %i, minibatch %i/%i, validation error %f %%' %
(
epoch,
minibatch_index + 1,
n_train_batches,
this_validation_loss * 100.
)
)
###############
# PREDICTIONS #
###############
# save and load
f = file(filename, 'wb')
cPickle.dump(classifier.__getstate__(), f, protocol=cPickle.HIGHEST_PROTOCOL)
f.close()
end_time = time.clock()
print >> sys.stderr, ('The code ran for %.2fm' % ((end_time - start_time) / 60.))
if action == 'predict':
# construct the CNN class
classifier_2 = CNN(
rng=rng,
input=x,
nkerns = nkerns,
batch_size = batch_size
)
print "...."
f = file(filename, 'rb')
classifier_2.__setstate__(cPickle.load(f))
f.close()
RET = []
for it in range(len(test_datasets)):
test_data = test_datasets[it]
N = len(test_data)
test_data = theano.shared(numpy.asarray(test_data, dtype=theano.config.floatX))
# just zeroes
test_labels = T.cast(theano.shared(numpy.asarray(numpy.zeros(batch_size), dtype=theano.config.floatX)), 'int32')
ppm = theano.function([index], classifier_2.layer3.pred_probs(),
givens={
x: test_data[index * batch_size: (index + 1) * batch_size],
y: test_labels
}, on_unused_input='warn')
# p : predictions, we need to take argmax, p is 3-dim: (# loop iterations x batch_size x 2)
p = [ppm(ii) for ii in xrange( N / batch_size)]
#p_one = sum(p, [])
#print p
p = numpy.array(p).reshape((N, 10))
print p
p = numpy.argmax(p, axis=1)
p = p.astype(int)
RET.append(p)
return RET
