1717from rbm import RBM
1818
1919
20+ # start-snippet-1
2021class DBN (object ):
2122 """Deep Belief Network
2223
@@ -65,7 +66,7 @@ def __init__(self, numpy_rng, theano_rng=None, n_ins=784,
6566 self .x = T .matrix ('x' ) # the data is presented as rasterized images
6667 self .y = T .ivector ('y' ) # the labels are presented as 1D vector
6768 # of [int] labels
68-
69+ # end-snippet-1
6970 # The DBN is an MLP, for which all weights of intermediate
7071 # layers are shared with a different RBM. We will first
7172 # construct the DBN as a deep multilayer perceptron, and when
@@ -174,12 +175,14 @@ def pretraining_functions(self, train_set_x, batch_size, k):
174175 persistent = None , k = k )
175176
176177 # compile the theano function
177- fn = theano .function (inputs = [index ,
178- theano .Param (learning_rate , default = 0.1 )],
179- outputs = cost ,
180- updates = updates ,
181- givens = {self .x :
182- train_set_x [batch_begin :batch_end ]})
178+ fn = theano .function (
179+ inputs = [index , theano .Param (learning_rate , default = 0.1 )],
180+ outputs = cost ,
181+ updates = updates ,
182+ givens = {
183+ self .x : train_set_x [batch_begin :batch_end ]
184+ }
185+ )
183186 # append `fn` to the list of functions
184187 pretrain_fns .append (fn )
185188
@@ -224,25 +227,45 @@ def build_finetune_functions(self, datasets, batch_size, learning_rate):
224227 for param , gparam in zip (self .params , gparams ):
225228 updates .append ((param , param - gparam * learning_rate ))
226229
227- train_fn = theano .function (inputs = [index ],
228- outputs = self .finetune_cost ,
229- updates = updates ,
230- givens = {self .x : train_set_x [index * batch_size :
231- (index + 1 ) * batch_size ],
232- self .y : train_set_y [index * batch_size :
233- (index + 1 ) * batch_size ]})
234-
235- test_score_i = theano .function ([index ], self .errors ,
236- givens = {self .x : test_set_x [index * batch_size :
237- (index + 1 ) * batch_size ],
238- self .y : test_set_y [index * batch_size :
239- (index + 1 ) * batch_size ]})
240-
241- valid_score_i = theano .function ([index ], self .errors ,
242- givens = {self .x : valid_set_x [index * batch_size :
243- (index + 1 ) * batch_size ],
244- self .y : valid_set_y [index * batch_size :
245- (index + 1 ) * batch_size ]})
230+ train_fn = theano .function (
231+ inputs = [index ],
232+ outputs = self .finetune_cost ,
233+ updates = updates ,
234+ givens = {
235+ self .x : train_set_x [
236+ index * batch_size : (index + 1 ) * batch_size
237+ ],
238+ self .y : train_set_y [
239+ index * batch_size : (index + 1 ) * batch_size
240+ ]
241+ }
242+ )
243+
244+ test_score_i = theano .function (
245+ [index ],
246+ self .errors ,
247+ givens = {
248+ self .x : test_set_x [
249+ index * batch_size : (index + 1 ) * batch_size
250+ ],
251+ self .y : test_set_y [
252+ index * batch_size : (index + 1 ) * batch_size
253+ ]
254+ }
255+ )
256+
257+ valid_score_i = theano .function (
258+ [index ],
259+ self .errors ,
260+ givens = {
261+ self .x : valid_set_x [
262+ index * batch_size : (index + 1 ) * batch_size
263+ ],
264+ self .y : valid_set_y [
265+ index * batch_size : (index + 1 ) * batch_size
266+ ]
267+ }
268+ )
246269
247270 # Create a function that scans the entire validation set
248271 def valid_score ():
@@ -296,6 +319,7 @@ def test_DBN(finetune_lr=0.1, pretraining_epochs=100,
296319 hidden_layers_sizes = [1000 , 1000 , 1000 ],
297320 n_outs = 10 )
298321
322+ # start-snippet-2
299323 #########################
300324 # PRETRAINING THE MODEL #
301325 #########################
@@ -319,21 +343,23 @@ def test_DBN(finetune_lr=0.1, pretraining_epochs=100,
319343 print numpy .mean (c )
320344
321345 end_time = time .clock ()
346+ # end-snippet-2
322347 print >> sys .stderr , ('The pretraining code for file ' +
323348 os .path .split (__file__ )[1 ] +
324349 ' ran for %.2fm' % ((end_time - start_time ) / 60. ))
325-
326350 ########################
327351 # FINETUNING THE MODEL #
328352 ########################
329353
330354 # get the training, validation and testing function for the model
331355 print '... getting the finetuning functions'
332356 train_fn , validate_model , test_model = dbn .build_finetune_functions (
333- datasets = datasets , batch_size = batch_size ,
334- learning_rate = finetune_lr )
357+ datasets = datasets ,
358+ batch_size = batch_size ,
359+ learning_rate = finetune_lr
360+ )
335361
336- print '... finetunning the model'
362+ print '... finetuning the model'
337363 # early-stopping parameters
338364 patience = 4 * n_train_batches # look as this many examples regardless
339365 patience_increase = 2. # wait this much longer when a new best is
@@ -342,7 +368,7 @@ def test_DBN(finetune_lr=0.1, pretraining_epochs=100,
342368 # considered significant
343369 validation_frequency = min (n_train_batches , patience / 2 )
344370 # go through this many
345- # minibatche before checking the network
371+ # minibatches before checking the network
346372 # on the validation set; in this case we
347373 # check every epoch
348374
@@ -365,16 +391,24 @@ def test_DBN(finetune_lr=0.1, pretraining_epochs=100,
365391
366392 validation_losses = validate_model ()
367393 this_validation_loss = numpy .mean (validation_losses )
368- print ('epoch %i, minibatch %i/%i, validation error %f %%' % \
369- (epoch , minibatch_index + 1 , n_train_batches ,
370- this_validation_loss * 100. ))
394+ print (
395+ 'epoch %i, minibatch %i/%i, validation error %f %%'
396+ % (
397+ epoch ,
398+ minibatch_index + 1 ,
399+ n_train_batches ,
400+ this_validation_loss * 100.
401+ )
402+ )
371403
372404 # if we got the best validation score until now
373405 if this_validation_loss < best_validation_loss :
374406
375407 #improve patience if loss improvement is good enough
376- if (this_validation_loss < best_validation_loss *
377- improvement_threshold ):
408+ if (
409+ this_validation_loss < best_validation_loss *
410+ improvement_threshold
411+ ):
378412 patience = max (patience , iter * patience_increase )
379413
380414 # save best validation score and iteration number
@@ -394,9 +428,12 @@ def test_DBN(finetune_lr=0.1, pretraining_epochs=100,
394428 break
395429
396430 end_time = time .clock ()
397- print (('Optimization complete with best validation score of %f %%,'
398- 'with test performance %f %%' ) %
399- (best_validation_loss * 100. , test_score * 100. ))
431+ print (
432+ (
433+ 'Optimization complete with best validation score of %f %%,'
434+ 'with test performance %f %%'
435+ ) % (best_validation_loss * 100. , test_score * 100. )
436+ )
400437 print >> sys .stderr , ('The fine tuning code for file ' +
401438 os .path .split (__file__ )[1 ] +
402439 ' ran for %.2fm' % ((end_time - start_time )
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