Mercurial > ift6266
view baseline/mlp/mlp_nist.py @ 509:860c755ddcff
argh, sorry about that
author | Dumitru Erhan <dumitru.erhan@gmail.com> |
---|---|
date | Tue, 01 Jun 2010 10:58:15 -0700 |
parents | 868f82777839 |
children |
line wrap: on
line source
""" This tutorial introduces the multilayer perceptron using Theano. A multilayer perceptron is a logistic regressor where instead of feeding the input to the logistic regression you insert a intermidiate layer, called the hidden layer, that has a nonlinear activation function (usually tanh or sigmoid) . One can use many such hidden layers making the architecture deep. The tutorial will also tackle the problem of MNIST digit classification. .. math:: f(x) = G( b^{(2)} + W^{(2)}( s( b^{(1)} + W^{(1)} x))), References: - textbooks: "Pattern Recognition and Machine Learning" - Christopher M. Bishop, section 5 TODO: recommended preprocessing, lr ranges, regularization ranges (explain to do lr first, then add regularization) """ __docformat__ = 'restructedtext en' import sys import pdb import numpy import pylab import theano import theano.tensor as T import time import theano.tensor.nnet import pylearn import theano,pylearn.version,ift6266 from pylearn.io import filetensor as ft from ift6266 import datasets data_path = '/data/lisa/data/nist/by_class/' class MLP(object): """Multi-Layer Perceptron Class A multilayer perceptron is a feedforward artificial neural network model that has one layer or more of hidden units and nonlinear activations. Intermidiate layers usually have as activation function thanh or the sigmoid function while the top layer is a softamx layer. """ def __init__(self, input, n_in, n_hidden, n_out,learning_rate,detection_mode): """Initialize the parameters for the multilayer perceptron :param input: symbolic variable that describes the input of the architecture (one minibatch) :param n_in: number of input units, the dimension of the space in which the datapoints lie :param n_hidden: number of hidden units :param n_out: number of output units, the dimension of the space in which the labels lie """ # initialize the parameters theta = (W1,b1,W2,b2) ; note that this # example contains only one hidden layer, but one can have as many # layers as he/she wishes, making the network deeper. The only # problem making the network deep this way is during learning, # backpropagation being unable to move the network from the starting # point towards; this is where pre-training helps, giving a good # starting point for backpropagation, but more about this in the # other tutorials # `W1` is initialized with `W1_values` which is uniformely sampled # from -6./sqrt(n_in+n_hidden) and 6./sqrt(n_in+n_hidden) # the output of uniform if converted using asarray to dtype # theano.config.floatX so that the code is runable on GPU W1_values = numpy.asarray( numpy.random.uniform( \ low = -numpy.sqrt(6./(n_in+n_hidden)), \ high = numpy.sqrt(6./(n_in+n_hidden)), \ size = (n_in, n_hidden)), dtype = theano.config.floatX) # `W2` is initialized with `W2_values` which is uniformely sampled # from -6./sqrt(n_hidden+n_out) and 6./sqrt(n_hidden+n_out) # the output of uniform if converted using asarray to dtype # theano.config.floatX so that the code is runable on GPU W2_values = numpy.asarray( numpy.random.uniform( low = -numpy.sqrt(6./(n_hidden+n_out)), \ high= numpy.sqrt(6./(n_hidden+n_out)),\ size= (n_hidden, n_out)), dtype = theano.config.floatX) self.W1 = theano.shared( value = W1_values ) self.b1 = theano.shared( value = numpy.zeros((n_hidden,), dtype= theano.config.floatX)) self.W2 = theano.shared( value = W2_values ) self.b2 = theano.shared( value = numpy.zeros((n_out,), dtype= theano.config.floatX)) #include the learning rate in the classifer so #we can modify it on the fly when we want lr_value=learning_rate self.lr=theano.shared(value=lr_value) # symbolic expression computing the values of the hidden layer self.hidden = T.tanh(T.dot(input, self.W1)+ self.b1) # symbolic expression computing the values of the top layer if(detection_mode==0): self.p_y_given_x= T.nnet.softmax(T.dot(self.hidden, self.W2)+self.b2) else: self.p_y_given_x= T.nnet.sigmoid(T.dot(self.hidden, self.W2)+self.b2) # self.y_out_sig= T.sigmoid(T.dot(self.hidden, self.W2)+self.b2) # compute prediction as class whose probability is maximal in # symbolic form self.y_pred = T.argmax( self.p_y_given_x, axis =1) # self.y_pred_sig = T.argmax( self.y_out_sig, axis =1) # L1 norm ; one regularization option is to enforce L1 norm to # be small self.L1 = abs(self.W1).sum() + abs(self.W2).sum() # square of L2 norm ; one regularization option is to enforce # square of L2 norm to be small self.L2_sqr = (self.W1**2).sum() + (self.W2**2).sum() def negative_log_likelihood(self, y): """Return the mean of the negative log-likelihood of the prediction of this model under a given target distribution. .. math:: \frac{1}{|\mathcal{D}|}\mathcal{L} (\theta=\{W,b\}, \mathcal{D}) = \frac{1}{|\mathcal{D}|}\sum_{i=0}^{|\mathcal{D}|} \log(P(Y=y^{(i)}|x^{(i)}, W,b)) \\ \ell (\theta=\{W,b\}, \mathcal{D}) :param y: corresponds to a vector that gives for each example the :correct label """ return -T.mean(T.log(self.p_y_given_x)[T.arange(y.shape[0]),y]) def cross_entropy(self, y): return -T.mean(T.log(self.p_y_given_x)[T.arange(y.shape[0]),y]+T.sum(T.log(1-self.p_y_given_x), axis=1)-T.log(1-self.p_y_given_x)[T.arange(y.shape[0]),y]) def errors(self, y): """Return a float representing the number of errors in the minibatch over the total number of examples of the minibatch """ # check if y has same dimension of y_pred if y.ndim != self.y_pred.ndim: raise TypeError('y should have the same shape as self.y_pred', ('y', target.type, 'y_pred', self.y_pred.type)) # check if y is of the correct datatype if y.dtype.startswith('int'): # the T.neq operator returns a vector of 0s and 1s, where 1 # represents a mistake in prediction return T.mean(T.neq(self.y_pred, y)) else: raise NotImplementedError() def mlp_get_nist_error(model_name='/u/mullerx/ift6266h10_sandbox_db/xvm_final_lr1_p073/8/best_model.npy.npz', data_set=0): # load the data set and create an mlp based on the dimensions of the model model=numpy.load(model_name) W1=model['W1'] W2=model['W2'] b1=model['b1'] b2=model['b2'] total_error_count=0.0 total_exemple_count=0.0 nb_error_count=0.0 nb_exemple_count=0.0 char_error_count=0.0 char_exemple_count=0.0 min_error_count=0.0 min_exemple_count=0.0 maj_error_count=0.0 maj_exemple_count=0.0 vtotal_error_count=0.0 vtotal_exemple_count=0.0 vnb_error_count=0.0 vnb_exemple_count=0.0 vchar_error_count=0.0 vchar_exemple_count=0.0 vmin_error_count=0.0 vmin_exemple_count=0.0 vmaj_error_count=0.0 vmaj_exemple_count=0.0 nbc_error_count=0.0 vnbc_error_count=0.0 if data_set==0: print 'using nist' dataset=datasets.nist_all() elif data_set==1: print 'using p07' dataset=datasets.nist_P07() elif data_set==2: print 'using pnist' dataset=datasets.PNIST07() #get the test error #use a batch size of 1 so we can get the sub-class error #without messing with matrices (will be upgraded later) test_score=0 temp=0 for xt,yt in dataset.test(1): total_exemple_count = total_exemple_count +1 #get activation for layer 1 a0=numpy.dot(numpy.transpose(W1),numpy.transpose(xt[0])) + b1 #add non linear function to layer 1 activation a0_out=numpy.tanh(a0) #get activation for output layer a1= numpy.dot(numpy.transpose(W2),a0_out) + b2 #add non linear function for output activation (softmax) a1_exp = numpy.exp(a1) sum_a1=numpy.sum(a1_exp) a1_out=a1_exp/sum_a1 predicted_class=numpy.argmax(a1_out) wanted_class=yt[0] if(predicted_class!=wanted_class): total_error_count = total_error_count +1 if(not(predicted_class==wanted_class or ( (((predicted_class+26)==wanted_class) or ((predicted_class-26)==wanted_class)) and wanted_class>9) )): nbc_error_count = nbc_error_count +1 #treat digit error if(wanted_class<10): nb_exemple_count=nb_exemple_count + 1 predicted_class=numpy.argmax(a1_out[0:10]) if(predicted_class!=wanted_class): nb_error_count = nb_error_count +1 if(wanted_class>9): char_exemple_count=char_exemple_count + 1 predicted_class=numpy.argmax(a1_out[10:62])+10 if((predicted_class!=wanted_class) and ((predicted_class+26)!=wanted_class) and ((predicted_class-26)!=wanted_class)): char_error_count = char_error_count +1 #minuscule if(wanted_class>9 and wanted_class<36): maj_exemple_count=maj_exemple_count + 1 predicted_class=numpy.argmax(a1_out[10:35])+10 if(predicted_class!=wanted_class): maj_error_count = maj_error_count +1 #majuscule if(wanted_class>35): min_exemple_count=min_exemple_count + 1 predicted_class=numpy.argmax(a1_out[36:62])+36 if(predicted_class!=wanted_class): min_error_count = min_error_count +1 vtest_score=0 vtemp=0 for xt,yt in dataset.valid(1): vtotal_exemple_count = vtotal_exemple_count +1 #get activation for layer 1 a0=numpy.dot(numpy.transpose(W1),numpy.transpose(xt[0])) + b1 #add non linear function to layer 1 activation a0_out=numpy.tanh(a0) #get activation for output layer a1= numpy.dot(numpy.transpose(W2),a0_out) + b2 #add non linear function for output activation (softmax) a1_exp = numpy.exp(a1) sum_a1=numpy.sum(a1_exp) a1_out=a1_exp/sum_a1 predicted_class=numpy.argmax(a1_out) wanted_class=yt[0] if(predicted_class!=wanted_class): vtotal_error_count = vtotal_error_count +1 if(not(predicted_class==wanted_class or ( (((predicted_class+26)==wanted_class) or ((predicted_class-26)==wanted_class)) and wanted_class>9) )): vnbc_error_count = nbc_error_count +1 #treat digit error if(wanted_class<10): vnb_exemple_count=vnb_exemple_count + 1 predicted_class=numpy.argmax(a1_out[0:10]) if(predicted_class!=wanted_class): vnb_error_count = vnb_error_count +1 if(wanted_class>9): vchar_exemple_count=vchar_exemple_count + 1 predicted_class=numpy.argmax(a1_out[10:62])+10 if((predicted_class!=wanted_class) and ((predicted_class+26)!=wanted_class) and ((predicted_class-26)!=wanted_class)): vchar_error_count = vchar_error_count +1 #minuscule if(wanted_class>9 and wanted_class<36): vmaj_exemple_count=vmaj_exemple_count + 1 predicted_class=numpy.argmax(a1_out[10:35])+10 if(predicted_class!=wanted_class): vmaj_error_count = vmaj_error_count +1 #majuscule if(wanted_class>35): vmin_exemple_count=vmin_exemple_count + 1 predicted_class=numpy.argmax(a1_out[36:62])+36 if(predicted_class!=wanted_class): vmin_error_count = vmin_error_count +1 print (('total error = %f') % ((total_error_count/total_exemple_count)*100.0)) print (('number error = %f') % ((nb_error_count/nb_exemple_count)*100.0)) print (('char error = %f') % ((char_error_count/char_exemple_count)*100.0)) print (('min error = %f') % ((min_error_count/min_exemple_count)*100.0)) print (('maj error = %f') % ((maj_error_count/maj_exemple_count)*100.0)) print (('36 error = %f') % ((nbc_error_count/total_exemple_count)*100.0)) print (('valid total error = %f') % ((vtotal_error_count/vtotal_exemple_count)*100.0)) print (('valid number error = %f') % ((vnb_error_count/vnb_exemple_count)*100.0)) print (('valid char error = %f') % ((vchar_error_count/vchar_exemple_count)*100.0)) print (('valid min error = %f') % ((vmin_error_count/vmin_exemple_count)*100.0)) print (('valid maj error = %f') % ((vmaj_error_count/vmaj_exemple_count)*100.0)) print (('valid 36 error = %f') % ((vnbc_error_count/vtotal_exemple_count)*100.0)) print (('num total = %d,%d') % (total_exemple_count,total_error_count)) print (('num nb = %d,%d') % (nb_exemple_count,nb_error_count)) print (('num min = %d,%d') % (min_exemple_count,min_error_count)) print (('num maj = %d,%d') % (maj_exemple_count,maj_error_count)) print (('num char = %d,%d') % (char_exemple_count,char_error_count)) total_error_count/=total_exemple_count nb_error_count/=nb_exemple_count char_error_count/=char_exemple_count min_error_count/=min_exemple_count maj_error_count/=maj_exemple_count nbc_error_count/=total_exemple_count vtotal_error_count/=vtotal_exemple_count vnb_error_count/=vnb_exemple_count vchar_error_count/=vchar_exemple_count vmin_error_count/=vmin_exemple_count vmaj_error_count/=vmaj_exemple_count vnbc_error_count/=vtotal_exemple_count return (total_error_count,nb_error_count,char_error_count,min_error_count,maj_error_count,nbc_error_count,\ vtotal_error_count,vnb_error_count,vchar_error_count,vmin_error_count,vmaj_error_count,vnbc_error_count) def jobman_get_error(state,channel): (all_t_error,nb_t_error,char_t_error,min_t_error,maj_t_error,nbc_t_error, all_v_error,nb_v_error,char_v_error,min_v_error,maj_v_error,nbc_v_error)=mlp_get_nist_error(data_set=state.data_set,\ model_name=state.model_name) state.all_t_error=all_t_error*100.0 state.nb_t_error=nb_t_error*100.0 state.char_t_error=char_t_error*100.0 state.min_t_error=min_t_error*100.0 state.maj_t_error=maj_t_error*100.0 state.nbc_t_error=nbc_t_error*100.0 state.all_v_error=all_v_error*100.0 state.nb_v_error=nb_v_error*100.0 state.char_v_error=char_v_error*100.0 state.min_v_error=min_v_error*100.0 state.maj_v_error=maj_v_error*100.0 state.nbc_v_error=nbc_v_error*100.0 pylearn.version.record_versions(state,[theano,ift6266,pylearn]) return channel.COMPLETE def mlp_full_nist( verbose = 1,\ adaptive_lr = 0,\ data_set=0,\ learning_rate=0.01,\ L1_reg = 0.00,\ L2_reg = 0.0001,\ nb_max_exemples=1000000,\ batch_size=20,\ nb_hidden = 30,\ nb_targets = 62, tau=1e6,\ lr_t2_factor=0.5,\ init_model=0,\ channel=0,\ detection_mode=0): if channel!=0: channel.save() configuration = [learning_rate,nb_max_exemples,nb_hidden,adaptive_lr] #save initial learning rate if classical adaptive lr is used initial_lr=learning_rate max_div_count=1000 optimal_test_error=0 total_validation_error_list = [] total_train_error_list = [] learning_rate_list=[] best_training_error=float('inf'); divergence_flag_list=[] if data_set==0: print 'using nist' dataset=datasets.nist_all() elif data_set==1: print 'using p07' dataset=datasets.nist_P07() elif data_set==2: print 'using pnist' dataset=datasets.PNIST07() ishape = (32,32) # this is the size of NIST images # allocate symbolic variables for the data x = T.fmatrix() # the data is presented as rasterized images y = T.lvector() # the labels are presented as 1D vector of # [long int] labels # construct the logistic regression class classifier = MLP( input=x,\ n_in=32*32,\ n_hidden=nb_hidden,\ n_out=nb_targets, learning_rate=learning_rate, detection_mode=detection_mode) # check if we want to initialise the weights with a previously calculated model # dimensions must be consistent between old model and current configuration!!!!!! (nb_hidden and nb_targets) if init_model!=0: print 'using old model' print init_model old_model=numpy.load(init_model) classifier.W1.value=old_model['W1'] classifier.W2.value=old_model['W2'] classifier.b1.value=old_model['b1'] classifier.b2.value=old_model['b2'] # the cost we minimize during training is the negative log likelihood of # the model plus the regularization terms (L1 and L2); cost is expressed # here symbolically if(detection_mode==0): cost = classifier.negative_log_likelihood(y) \ + L1_reg * classifier.L1 \ + L2_reg * classifier.L2_sqr else: cost = classifier.cross_entropy(y) \ + L1_reg * classifier.L1 \ + L2_reg * classifier.L2_sqr # compiling a theano function that computes the mistakes that are made by # the model on a minibatch test_model = theano.function([x,y], classifier.errors(y)) # compute the gradient of cost with respect to theta = (W1, b1, W2, b2) g_W1 = T.grad(cost, classifier.W1) g_b1 = T.grad(cost, classifier.b1) g_W2 = T.grad(cost, classifier.W2) g_b2 = T.grad(cost, classifier.b2) # specify how to update the parameters of the model as a dictionary updates = \ { classifier.W1: classifier.W1 - classifier.lr*g_W1 \ , classifier.b1: classifier.b1 - classifier.lr*g_b1 \ , classifier.W2: classifier.W2 - classifier.lr*g_W2 \ , classifier.b2: classifier.b2 - classifier.lr*g_b2 } # 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([x, y], cost, updates = updates ) #conditions for stopping the adaptation: #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) #2) validation error is going up twice in a row(probable overfitting) # This means we no longer stop on slow convergence as low learning rates stopped # too fast but instead we will wait for the valid error going up 3 times in a row # We save the curb of the validation error so we can always go back to check on it # and we save the absolute best model anyway, so we might as well explore # a bit when diverging #approximate number of samples in the nist training set #this is just to have a validation frequency #roughly proportionnal to the original nist training set n_minibatches = 650000/batch_size patience =2*nb_max_exemples/batch_size #in units of minibatch validation_frequency = n_minibatches/4 best_validation_loss = float('inf') best_iter = 0 test_score = 0. start_time = time.clock() time_n=0 #in unit of exemples minibatch_index=0 epoch=0 temp=0 divergence_flag=0 print 'starting training' sys.stdout.flush() while(minibatch_index*batch_size<nb_max_exemples): for x, y in dataset.train(batch_size): #if we are using the classic learning rate deacay, adjust it before training of current mini-batch if adaptive_lr==2: classifier.lr.value = tau*initial_lr/(tau+time_n) #train model cost_ij = train_model(x,y) if (minibatch_index) % validation_frequency == 0: #save the current learning rate learning_rate_list.append(classifier.lr.value) divergence_flag_list.append(divergence_flag) # compute the validation error this_validation_loss = 0. temp=0 for xv,yv in dataset.valid(1): # sum up the errors for each minibatch this_validation_loss += test_model(xv,yv) temp=temp+1 # get the average by dividing with the number of minibatches this_validation_loss /= temp #save the validation loss total_validation_error_list.append(this_validation_loss) print(('epoch %i, minibatch %i, learning rate %f current validation error %f ') % (epoch, minibatch_index+1,classifier.lr.value, this_validation_loss*100.)) sys.stdout.flush() #save temp results to check during training numpy.savez('temp_results.npy',config=configuration,total_validation_error_list=total_validation_error_list,\ learning_rate_list=learning_rate_list, divergence_flag_list=divergence_flag_list) # if we got the best validation score until now if this_validation_loss < best_validation_loss: # save best validation score and iteration number best_validation_loss = this_validation_loss best_iter = minibatch_index #reset divergence flag divergence_flag=0 #save the best model. Overwrite the current saved best model so #we only keep the best numpy.savez('best_model.npy', config=configuration, W1=classifier.W1.value, W2=classifier.W2.value, b1=classifier.b1.value,\ b2=classifier.b2.value, minibatch_index=minibatch_index) # test it on the test set test_score = 0. temp =0 for xt,yt in dataset.test(batch_size): test_score += test_model(xt,yt) temp = temp+1 test_score /= temp print(('epoch %i, minibatch %i, test error of best ' 'model %f %%') % (epoch, minibatch_index+1, test_score*100.)) sys.stdout.flush() optimal_test_error=test_score # if the validation error is going up, we are overfitting (or oscillating) # check if we are allowed to continue and if we will adjust the learning rate elif this_validation_loss >= best_validation_loss: # In non-classic learning rate decay, we modify the weight only when # validation error is going up if adaptive_lr==1: classifier.lr.value=classifier.lr.value*lr_t2_factor #cap the patience so we are allowed to diverge max_div_count times #if we are going up max_div_count in a row, we will stop immediatelty by modifying the patience divergence_flag = divergence_flag +1 #calculate the test error at this point and exit # test it on the test set test_score = 0. temp=0 for xt,yt in dataset.test(batch_size): test_score += test_model(xt,yt) temp=temp+1 test_score /= temp print ' validation error is going up, possibly stopping soon' print((' epoch %i, minibatch %i, test error of best ' 'model %f %%') % (epoch, minibatch_index+1, test_score*100.)) sys.stdout.flush() # check early stop condition if divergence_flag==max_div_count: minibatch_index=nb_max_exemples print 'we have diverged, early stopping kicks in' break #check if we have seen enough exemples #force one epoch at least if epoch>0 and minibatch_index*batch_size>nb_max_exemples: break time_n= time_n + batch_size minibatch_index = minibatch_index + 1 # we have finished looping through the training set epoch = epoch+1 end_time = time.clock() print(('Optimization complete. Best validation score of %f %% ' 'obtained at iteration %i, with test performance %f %%') % (best_validation_loss * 100., best_iter, test_score*100.)) print ('The code ran for %f minutes' % ((end_time-start_time)/60.)) print minibatch_index sys.stdout.flush() #save the model and the weights numpy.savez('model.npy', config=configuration, W1=classifier.W1.value,W2=classifier.W2.value, b1=classifier.b1.value,b2=classifier.b2.value) numpy.savez('results.npy',config=configuration,total_train_error_list=total_train_error_list,total_validation_error_list=total_validation_error_list,\ learning_rate_list=learning_rate_list, divergence_flag_list=divergence_flag_list) return (best_training_error*100.0,best_validation_loss * 100.,optimal_test_error*100.,best_iter*batch_size,(end_time-start_time)/60) if __name__ == '__main__': mlp_full_mnist() def jobman_mlp_full_nist(state,channel): (train_error,validation_error,test_error,nb_exemples,time)=mlp_full_nist(learning_rate=state.learning_rate,\ nb_max_exemples=state.nb_max_exemples,\ nb_hidden=state.nb_hidden,\ adaptive_lr=state.adaptive_lr,\ tau=state.tau,\ verbose = state.verbose,\ lr_t2_factor=state.lr_t2_factor, data_set=state.data_set, init_model=state.init_model, detection_mode = state.detection_mode,\ channel=channel) state.train_error=train_error state.validation_error=validation_error state.test_error=test_error state.nb_exemples=nb_exemples state.time=time pylearn.version.record_versions(state,[theano,ift6266,pylearn]) return channel.COMPLETE