Mercurial > ift6266
annotate baseline/mlp/mlp_nist.py @ 404:1509b9bba4cc
added digit/char error
author | xaviermuller |
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date | Wed, 28 Apr 2010 11:45:14 -0400 |
parents | 60a4432b8071 |
children | 195f95c3d461 |
rev | line source |
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110 | 1 """ |
2 This tutorial introduces the multilayer perceptron using Theano. | |
3 | |
4 A multilayer perceptron is a logistic regressor where | |
5 instead of feeding the input to the logistic regression you insert a | |
6 intermidiate layer, called the hidden layer, that has a nonlinear | |
7 activation function (usually tanh or sigmoid) . One can use many such | |
8 hidden layers making the architecture deep. The tutorial will also tackle | |
9 the problem of MNIST digit classification. | |
10 | |
11 .. math:: | |
12 | |
13 f(x) = G( b^{(2)} + W^{(2)}( s( b^{(1)} + W^{(1)} x))), | |
14 | |
15 References: | |
16 | |
17 - textbooks: "Pattern Recognition and Machine Learning" - | |
18 Christopher M. Bishop, section 5 | |
19 | |
20 TODO: recommended preprocessing, lr ranges, regularization ranges (explain | |
21 to do lr first, then add regularization) | |
22 | |
23 """ | |
24 __docformat__ = 'restructedtext en' | |
25 | |
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26 import sys |
110 | 27 import pdb |
28 import numpy | |
29 import pylab | |
30 import theano | |
31 import theano.tensor as T | |
32 import time | |
33 import theano.tensor.nnet | |
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34 import pylearn |
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35 import theano,pylearn.version,ift6266 |
110 | 36 from pylearn.io import filetensor as ft |
322 | 37 from ift6266 import datasets |
110 | 38 |
39 data_path = '/data/lisa/data/nist/by_class/' | |
40 | |
41 class MLP(object): | |
42 """Multi-Layer Perceptron Class | |
43 | |
44 A multilayer perceptron is a feedforward artificial neural network model | |
45 that has one layer or more of hidden units and nonlinear activations. | |
46 Intermidiate layers usually have as activation function thanh or the | |
47 sigmoid function while the top layer is a softamx layer. | |
48 """ | |
49 | |
50 | |
51 | |
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52 def __init__(self, input, n_in, n_hidden, n_out,learning_rate): |
110 | 53 """Initialize the parameters for the multilayer perceptron |
54 | |
55 :param input: symbolic variable that describes the input of the | |
56 architecture (one minibatch) | |
57 | |
58 :param n_in: number of input units, the dimension of the space in | |
59 which the datapoints lie | |
60 | |
61 :param n_hidden: number of hidden units | |
62 | |
63 :param n_out: number of output units, the dimension of the space in | |
64 which the labels lie | |
65 | |
66 """ | |
67 | |
68 # initialize the parameters theta = (W1,b1,W2,b2) ; note that this | |
69 # example contains only one hidden layer, but one can have as many | |
70 # layers as he/she wishes, making the network deeper. The only | |
71 # problem making the network deep this way is during learning, | |
72 # backpropagation being unable to move the network from the starting | |
73 # point towards; this is where pre-training helps, giving a good | |
74 # starting point for backpropagation, but more about this in the | |
75 # other tutorials | |
76 | |
77 # `W1` is initialized with `W1_values` which is uniformely sampled | |
78 # from -6./sqrt(n_in+n_hidden) and 6./sqrt(n_in+n_hidden) | |
79 # the output of uniform if converted using asarray to dtype | |
80 # theano.config.floatX so that the code is runable on GPU | |
81 W1_values = numpy.asarray( numpy.random.uniform( \ | |
82 low = -numpy.sqrt(6./(n_in+n_hidden)), \ | |
83 high = numpy.sqrt(6./(n_in+n_hidden)), \ | |
84 size = (n_in, n_hidden)), dtype = theano.config.floatX) | |
85 # `W2` is initialized with `W2_values` which is uniformely sampled | |
86 # from -6./sqrt(n_hidden+n_out) and 6./sqrt(n_hidden+n_out) | |
87 # the output of uniform if converted using asarray to dtype | |
88 # theano.config.floatX so that the code is runable on GPU | |
89 W2_values = numpy.asarray( numpy.random.uniform( | |
90 low = -numpy.sqrt(6./(n_hidden+n_out)), \ | |
91 high= numpy.sqrt(6./(n_hidden+n_out)),\ | |
92 size= (n_hidden, n_out)), dtype = theano.config.floatX) | |
93 | |
94 self.W1 = theano.shared( value = W1_values ) | |
95 self.b1 = theano.shared( value = numpy.zeros((n_hidden,), | |
96 dtype= theano.config.floatX)) | |
97 self.W2 = theano.shared( value = W2_values ) | |
98 self.b2 = theano.shared( value = numpy.zeros((n_out,), | |
99 dtype= theano.config.floatX)) | |
100 | |
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101 #include the learning rate in the classifer so |
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102 #we can modify it on the fly when we want |
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103 lr_value=learning_rate |
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104 self.lr=theano.shared(value=lr_value) |
110 | 105 # symbolic expression computing the values of the hidden layer |
106 self.hidden = T.tanh(T.dot(input, self.W1)+ self.b1) | |
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107 |
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108 |
110 | 109 |
110 # symbolic expression computing the values of the top layer | |
111 self.p_y_given_x= T.nnet.softmax(T.dot(self.hidden, self.W2)+self.b2) | |
112 | |
113 # compute prediction as class whose probability is maximal in | |
114 # symbolic form | |
115 self.y_pred = T.argmax( self.p_y_given_x, axis =1) | |
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116 self.y_pred_num = T.argmax( self.p_y_given_x[0:9], axis =1) |
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117 |
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118 |
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119 |
110 | 120 |
121 # L1 norm ; one regularization option is to enforce L1 norm to | |
122 # be small | |
123 self.L1 = abs(self.W1).sum() + abs(self.W2).sum() | |
124 | |
125 # square of L2 norm ; one regularization option is to enforce | |
126 # square of L2 norm to be small | |
127 self.L2_sqr = (self.W1**2).sum() + (self.W2**2).sum() | |
128 | |
129 | |
130 | |
131 def negative_log_likelihood(self, y): | |
132 """Return the mean of the negative log-likelihood of the prediction | |
133 of this model under a given target distribution. | |
134 | |
135 .. math:: | |
136 | |
137 \frac{1}{|\mathcal{D}|}\mathcal{L} (\theta=\{W,b\}, \mathcal{D}) = | |
138 \frac{1}{|\mathcal{D}|}\sum_{i=0}^{|\mathcal{D}|} \log(P(Y=y^{(i)}|x^{(i)}, W,b)) \\ | |
139 \ell (\theta=\{W,b\}, \mathcal{D}) | |
140 | |
141 | |
142 :param y: corresponds to a vector that gives for each example the | |
143 :correct label | |
144 """ | |
145 return -T.mean(T.log(self.p_y_given_x)[T.arange(y.shape[0]),y]) | |
146 | |
147 | |
148 | |
149 | |
150 def errors(self, y): | |
151 """Return a float representing the number of errors in the minibatch | |
152 over the total number of examples of the minibatch | |
153 """ | |
154 | |
155 # check if y has same dimension of y_pred | |
156 if y.ndim != self.y_pred.ndim: | |
157 raise TypeError('y should have the same shape as self.y_pred', | |
158 ('y', target.type, 'y_pred', self.y_pred.type)) | |
159 # check if y is of the correct datatype | |
160 if y.dtype.startswith('int'): | |
161 # the T.neq operator returns a vector of 0s and 1s, where 1 | |
162 # represents a mistake in prediction | |
163 return T.mean(T.neq(self.y_pred, y)) | |
164 else: | |
165 raise NotImplementedError() | |
166 | |
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167 def mlp_get_nist_error(model_name='/u/mullerx/ift6266h10_sandbox_db/xvm_final_lr1_p073/8/best_model.npy.npz', |
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168 data_set=0): |
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169 |
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170 |
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171 |
404 | 172 |
173 | |
174 | |
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175 |
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176 # load the data set and create an mlp based on the dimensions of the model |
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177 model=numpy.load(model_name) |
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178 W1=model['W1'] |
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179 W2=model['W2'] |
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180 b1=model['b1'] |
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181 b2=model['b2'] |
404 | 182 |
183 total_error_count=0.0 | |
184 total_exemple_count=0.0 | |
185 | |
186 nb_error_count=0.0 | |
187 nb_exemple_count=0.0 | |
188 | |
189 char_error_count=0.0 | |
190 char_exemple_count=0.0 | |
191 | |
192 min_error_count=0.0 | |
193 min_exemple_count=0.0 | |
194 | |
195 maj_error_count=0.0 | |
196 maj_exemple_count=0.0 | |
197 | |
198 | |
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199 |
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200 if data_set==0: |
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201 dataset=datasets.nist_all() |
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202 elif data_set==1: |
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203 dataset=datasets.nist_P07() |
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204 |
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205 |
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206 |
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207 #get the test error |
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208 #use a batch size of 1 so we can get the sub-class error |
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209 #without messing with matrices (will be upgraded later) |
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210 test_score=0 |
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211 temp=0 |
404 | 212 for xt,yt in dataset.test(1): |
213 | |
214 total_exemple_count = total_exemple_count +1 | |
215 #get activation for layer 1 | |
216 a0=numpy.dot(numpy.transpose(W1),numpy.transpose(xt[0])) + b1 | |
217 #add non linear function to layer 1 activation | |
218 a0_out=numpy.tanh(a0) | |
219 | |
220 #get activation for output layer | |
221 a1= numpy.dot(numpy.transpose(W2),a0_out) + b2 | |
222 #add non linear function for output activation (softmax) | |
223 a1_exp = numpy.exp(a1) | |
224 sum_a1=numpy.sum(a1_exp) | |
225 a1_out=a1_exp/sum_a1 | |
226 | |
227 predicted_class=numpy.argmax(a1_out) | |
228 wanted_class=yt[0] | |
229 if(predicted_class!=wanted_class): | |
230 total_error_count = total_error_count +1 | |
231 | |
232 #treat digit error | |
233 if(wanted_class<10): | |
234 nb_exemple_count=nb_exemple_count + 1 | |
235 predicted_class=numpy.argmax(a1_out[0:10]) | |
236 if(predicted_class!=wanted_class): | |
237 nb_error_count = nb_error_count +1 | |
238 | |
239 if(wanted_class>9): | |
240 char_exemple_count=char_exemple_count + 1 | |
241 predicted_class=numpy.argmax(a1_out[10:62])+10 | |
242 if((predicted_class!=wanted_class) and ((predicted_class+26)!=wanted_class) and ((predicted_class-26)!=wanted_class)): | |
243 char_error_count = char_error_count +1 | |
244 | |
245 | |
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246 |
404 | 247 print (('total error = %f') % ((total_error_count/total_exemple_count)*100.0)) |
248 print (('number error = %f') % ((nb_error_count/nb_exemple_count)*100.0)) | |
249 print (('char error = %f') % ((char_error_count/char_exemple_count)*100.0)) | |
250 return (total_error_count/total_exemple_count)*100.0 | |
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251 |
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252 |
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253 |
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254 |
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255 |
110 | 256 |
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257 def mlp_full_nist( verbose = 1,\ |
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258 adaptive_lr = 0,\ |
322 | 259 data_set=0,\ |
110 | 260 learning_rate=0.01,\ |
261 L1_reg = 0.00,\ | |
262 L2_reg = 0.0001,\ | |
263 nb_max_exemples=1000000,\ | |
264 batch_size=20,\ | |
322 | 265 nb_hidden = 30,\ |
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266 nb_targets = 62, |
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267 tau=1e6,\ |
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268 lr_t2_factor=0.5,\ |
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269 init_model=0,\ |
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270 channel=0): |
110 | 271 |
272 | |
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273 if channel!=0: |
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274 channel.save() |
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275 configuration = [learning_rate,nb_max_exemples,nb_hidden,adaptive_lr] |
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276 |
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277 #save initial learning rate if classical adaptive lr is used |
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278 initial_lr=learning_rate |
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279 max_div_count=1000 |
323 | 280 |
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281 |
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282 total_validation_error_list = [] |
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283 total_train_error_list = [] |
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284 learning_rate_list=[] |
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285 best_training_error=float('inf'); |
323 | 286 divergence_flag_list=[] |
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287 |
322 | 288 if data_set==0: |
378 | 289 print 'using nist' |
322 | 290 dataset=datasets.nist_all() |
323 | 291 elif data_set==1: |
378 | 292 print 'using p07' |
323 | 293 dataset=datasets.nist_P07() |
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294 elif data_set==2: |
378 | 295 print 'using pnist' |
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296 dataset=datasets.PNIST07() |
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297 |
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298 |
110 | 299 |
300 | |
301 ishape = (32,32) # this is the size of NIST images | |
302 | |
303 # allocate symbolic variables for the data | |
304 x = T.fmatrix() # the data is presented as rasterized images | |
305 y = T.lvector() # the labels are presented as 1D vector of | |
306 # [long int] labels | |
307 | |
322 | 308 |
110 | 309 # construct the logistic regression class |
322 | 310 classifier = MLP( input=x,\ |
110 | 311 n_in=32*32,\ |
312 n_hidden=nb_hidden,\ | |
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313 n_out=nb_targets, |
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314 learning_rate=learning_rate) |
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315 |
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316 |
338
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317 # check if we want to initialise the weights with a previously calculated model |
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318 # dimensions must be consistent between old model and current configuration!!!!!! (nb_hidden and nb_targets) |
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319 if init_model!=0: |
378 | 320 print 'using old model' |
321 print init_model | |
338
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322 old_model=numpy.load(init_model) |
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323 classifier.W1.value=old_model['W1'] |
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324 classifier.W2.value=old_model['W2'] |
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325 classifier.b1.value=old_model['b1'] |
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326 classifier.b2.value=old_model['b2'] |
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327 |
110 | 328 |
329 # the cost we minimize during training is the negative log likelihood of | |
330 # the model plus the regularization terms (L1 and L2); cost is expressed | |
331 # here symbolically | |
332 cost = classifier.negative_log_likelihood(y) \ | |
333 + L1_reg * classifier.L1 \ | |
334 + L2_reg * classifier.L2_sqr | |
335 | |
336 # compiling a theano function that computes the mistakes that are made by | |
337 # the model on a minibatch | |
338 test_model = theano.function([x,y], classifier.errors(y)) | |
339 | |
340 # compute the gradient of cost with respect to theta = (W1, b1, W2, b2) | |
341 g_W1 = T.grad(cost, classifier.W1) | |
342 g_b1 = T.grad(cost, classifier.b1) | |
343 g_W2 = T.grad(cost, classifier.W2) | |
344 g_b2 = T.grad(cost, classifier.b2) | |
345 | |
346 # specify how to update the parameters of the model as a dictionary | |
347 updates = \ | |
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348 { classifier.W1: classifier.W1 - classifier.lr*g_W1 \ |
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349 , classifier.b1: classifier.b1 - classifier.lr*g_b1 \ |
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350 , classifier.W2: classifier.W2 - classifier.lr*g_W2 \ |
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351 , classifier.b2: classifier.b2 - classifier.lr*g_b2 } |
110 | 352 |
353 # compiling a theano function `train_model` that returns the cost, but in | |
354 # the same time updates the parameter of the model based on the rules | |
355 # defined in `updates` | |
356 train_model = theano.function([x, y], cost, updates = updates ) | |
322 | 357 |
358 | |
359 | |
110 | 360 |
361 | |
362 | |
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363 |
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364 |
110 | 365 |
366 #conditions for stopping the adaptation: | |
323 | 367 #1) we have reached nb_max_exemples (this is rounded up to be a multiple of the train size so we always do at least 1 epoch) |
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368 #2) validation error is going up twice in a row(probable overfitting) |
110 | 369 |
370 # This means we no longer stop on slow convergence as low learning rates stopped | |
323 | 371 # too fast but instead we will wait for the valid error going up 3 times in a row |
372 # We save the curb of the validation error so we can always go back to check on it | |
373 # and we save the absolute best model anyway, so we might as well explore | |
374 # a bit when diverging | |
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375 |
323 | 376 #approximate number of samples in the nist training set |
322 | 377 #this is just to have a validation frequency |
323 | 378 #roughly proportionnal to the original nist training set |
322 | 379 n_minibatches = 650000/batch_size |
380 | |
381 | |
323 | 382 patience =2*nb_max_exemples/batch_size #in units of minibatch |
110 | 383 validation_frequency = n_minibatches/4 |
384 | |
385 | |
386 | |
387 | |
322 | 388 |
110 | 389 best_validation_loss = float('inf') |
390 best_iter = 0 | |
391 test_score = 0. | |
392 start_time = time.clock() | |
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393 time_n=0 #in unit of exemples |
322 | 394 minibatch_index=0 |
395 epoch=0 | |
396 temp=0 | |
323 | 397 divergence_flag=0 |
322 | 398 |
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399 |
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400 |
355
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401 |
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402 print 'starting training' |
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403 sys.stdout.flush() |
322 | 404 while(minibatch_index*batch_size<nb_max_exemples): |
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405 |
322 | 406 for x, y in dataset.train(batch_size): |
110 | 407 |
323 | 408 #if we are using the classic learning rate deacay, adjust it before training of current mini-batch |
322 | 409 if adaptive_lr==2: |
410 classifier.lr.value = tau*initial_lr/(tau+time_n) | |
411 | |
412 | |
413 #train model | |
414 cost_ij = train_model(x,y) | |
415 | |
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416 if (minibatch_index) % validation_frequency == 0: |
322 | 417 #save the current learning rate |
418 learning_rate_list.append(classifier.lr.value) | |
323 | 419 divergence_flag_list.append(divergence_flag) |
338
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420 |
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421 |
322 | 422 |
423 # compute the validation error | |
424 this_validation_loss = 0. | |
425 temp=0 | |
426 for xv,yv in dataset.valid(1): | |
427 # sum up the errors for each minibatch | |
323 | 428 this_validation_loss += test_model(xv,yv) |
322 | 429 temp=temp+1 |
430 # get the average by dividing with the number of minibatches | |
431 this_validation_loss /= temp | |
432 #save the validation loss | |
433 total_validation_error_list.append(this_validation_loss) | |
355
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434 |
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435 print(('epoch %i, minibatch %i, learning rate %f current validation error %f ') % |
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436 (epoch, minibatch_index+1,classifier.lr.value, |
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437 this_validation_loss*100.)) |
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438 sys.stdout.flush() |
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439 |
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440 #save temp results to check during training |
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441 numpy.savez('temp_results.npy',config=configuration,total_validation_error_list=total_validation_error_list,\ |
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442 learning_rate_list=learning_rate_list, divergence_flag_list=divergence_flag_list) |
322 | 443 |
444 # if we got the best validation score until now | |
445 if this_validation_loss < best_validation_loss: | |
446 # save best validation score and iteration number | |
447 best_validation_loss = this_validation_loss | |
448 best_iter = minibatch_index | |
323 | 449 #reset divergence flag |
450 divergence_flag=0 | |
451 | |
452 #save the best model. Overwrite the current saved best model so | |
453 #we only keep the best | |
454 numpy.savez('best_model.npy', config=configuration, W1=classifier.W1.value, W2=classifier.W2.value, b1=classifier.b1.value,\ | |
455 b2=classifier.b2.value, minibatch_index=minibatch_index) | |
456 | |
322 | 457 # test it on the test set |
458 test_score = 0. | |
459 temp =0 | |
460 for xt,yt in dataset.test(batch_size): | |
461 test_score += test_model(xt,yt) | |
462 temp = temp+1 | |
463 test_score /= temp | |
355
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464 |
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465 print(('epoch %i, minibatch %i, test error of best ' |
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466 'model %f %%') % |
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467 (epoch, minibatch_index+1, |
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468 test_score*100.)) |
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469 sys.stdout.flush() |
322 | 470 |
471 # if the validation error is going up, we are overfitting (or oscillating) | |
323 | 472 # check if we are allowed to continue and if we will adjust the learning rate |
322 | 473 elif this_validation_loss >= best_validation_loss: |
323 | 474 |
475 | |
476 # In non-classic learning rate decay, we modify the weight only when | |
477 # validation error is going up | |
478 if adaptive_lr==1: | |
479 classifier.lr.value=classifier.lr.value*lr_t2_factor | |
480 | |
481 | |
482 #cap the patience so we are allowed to diverge max_div_count times | |
483 #if we are going up max_div_count in a row, we will stop immediatelty by modifying the patience | |
484 divergence_flag = divergence_flag +1 | |
485 | |
486 | |
322 | 487 #calculate the test error at this point and exit |
488 # test it on the test set | |
489 test_score = 0. | |
490 temp=0 | |
491 for xt,yt in dataset.test(batch_size): | |
492 test_score += test_model(xt,yt) | |
493 temp=temp+1 | |
494 test_score /= temp | |
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495 |
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496 print ' validation error is going up, possibly stopping soon' |
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497 print((' epoch %i, minibatch %i, test error of best ' |
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498 'model %f %%') % |
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499 (epoch, minibatch_index+1, |
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500 test_score*100.)) |
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501 sys.stdout.flush() |
322 | 502 |
503 | |
504 | |
323 | 505 # check early stop condition |
506 if divergence_flag==max_div_count: | |
507 minibatch_index=nb_max_exemples | |
508 print 'we have diverged, early stopping kicks in' | |
509 break | |
510 | |
511 #check if we have seen enough exemples | |
512 #force one epoch at least | |
513 if epoch>0 and minibatch_index*batch_size>nb_max_exemples: | |
322 | 514 break |
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515 |
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516 |
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517 |
322 | 518 |
519 | |
520 time_n= time_n + batch_size | |
323 | 521 minibatch_index = minibatch_index + 1 |
522 | |
523 # we have finished looping through the training set | |
322 | 524 epoch = epoch+1 |
110 | 525 end_time = time.clock() |
355
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526 |
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527 print(('Optimization complete. Best validation score of %f %% ' |
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528 'obtained at iteration %i, with test performance %f %%') % |
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529 (best_validation_loss * 100., best_iter, test_score*100.)) |
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530 print ('The code ran for %f minutes' % ((end_time-start_time)/60.)) |
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531 print minibatch_index |
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532 sys.stdout.flush() |
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533 |
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534 #save the model and the weights |
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535 numpy.savez('model.npy', config=configuration, W1=classifier.W1.value,W2=classifier.W2.value, b1=classifier.b1.value,b2=classifier.b2.value) |
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536 numpy.savez('results.npy',config=configuration,total_train_error_list=total_train_error_list,total_validation_error_list=total_validation_error_list,\ |
323 | 537 learning_rate_list=learning_rate_list, divergence_flag_list=divergence_flag_list) |
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538 |
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539 return (best_training_error*100.0,best_validation_loss * 100.,test_score*100.,best_iter*batch_size,(end_time-start_time)/60) |
110 | 540 |
541 | |
542 if __name__ == '__main__': | |
543 mlp_full_mnist() | |
544 | |
545 def jobman_mlp_full_nist(state,channel): | |
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546 (train_error,validation_error,test_error,nb_exemples,time)=mlp_full_nist(learning_rate=state.learning_rate,\ |
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547 nb_max_exemples=state.nb_max_exemples,\ |
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548 nb_hidden=state.nb_hidden,\ |
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549 adaptive_lr=state.adaptive_lr,\ |
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550 tau=state.tau,\ |
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551 verbose = state.verbose,\ |
324 | 552 lr_t2_factor=state.lr_t2_factor, |
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553 data_set=state.data_set, |
378 | 554 init_model=state.init_model, |
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555 channel=channel) |
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556 state.train_error=train_error |
110 | 557 state.validation_error=validation_error |
558 state.test_error=test_error | |
559 state.nb_exemples=nb_exemples | |
560 state.time=time | |
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561 pylearn.version.record_versions(state,[theano,ift6266,pylearn]) |
110 | 562 return channel.COMPLETE |
563 | |
564 |