ift6266: deep/stacked_dae/old/stacked

comparison deep/stacked_dae/old/stacked_dae.py @ 265:c8fe09a65039

Déplacer le nouveau code de stacked_dae de v2 vers le répertoire de base 'stacked_dae', et bougé le vieux code vers le répertoire 'old'

author	fsavard
date	Fri, 19 Mar 2010 10:54:39 -0400
parents	deep/stacked_dae/stacked_dae.py@acb942530923
children

comparison

equal deleted inserted replaced

-:3c54cb3713ef
+:c8fe09a65039
+#!/usr/bin/python
+# coding: utf-8
+import numpy
+import theano
+import time
+import theano.tensor as T
+from theano.tensor.shared_randomstreams import RandomStreams
+import copy
+from utils import update_locals
+# taken from LeDeepNet/daa.py
+# has a special case when taking log(0) (defined =0)
+# modified to not take the mean anymore
+from theano.tensor.xlogx import xlogx, xlogy0
+# it's target*log(output)
+def binary_cross_entropy(target, output, sum_axis=1):
+XE = xlogy0(target, output) + xlogy0((1 - target), (1 - output))
+return -T.sum(XE, axis=sum_axis)
+class LogisticRegression(object):
+def __init__(self, input, n_in, n_out):
+# initialize with 0 the weights W as a matrix of shape (n_in, n_out)
+self.W = theano.shared( value=numpy.zeros((n_in,n_out),
+dtype = theano.config.floatX) )
+# initialize the baises b as a vector of n_out 0s
+self.b = theano.shared( value=numpy.zeros((n_out,),
+dtype = theano.config.floatX) )
+# compute vector of class-membership probabilities in symbolic form
+self.p_y_given_x = T.nnet.softmax(T.dot(input, self.W)+self.b)
+# compute prediction as class whose probability is maximal in
+# symbolic form
+self.y_pred=T.argmax(self.p_y_given_x, axis=1)
+# list of parameters for this layer
+self.params = [self.W, self.b]
+def negative_log_likelihood(self, y):
+return -T.mean(T.log(self.p_y_given_x)[T.arange(y.shape[0]),y])
+def errors(self, y):
+# 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()
+class SigmoidalLayer(object):
+def __init__(self, rng, input, n_in, n_out):
+self.input = input
+W_values = numpy.asarray( rng.uniform( \
+low = -numpy.sqrt(6./(n_in+n_out)), \
+high = numpy.sqrt(6./(n_in+n_out)), \
+size = (n_in, n_out)), dtype = theano.config.floatX)
+self.W = theano.shared(value = W_values)
+b_values = numpy.zeros((n_out,), dtype= theano.config.floatX)
+self.b = theano.shared(value= b_values)
+self.output = T.nnet.sigmoid(T.dot(input, self.W) + self.b)
+self.params = [self.W, self.b]
+class dA(object):
+def __init__(self, n_visible= 784, n_hidden= 500, corruption_level = 0.1,\
+input = None, shared_W = None, shared_b = None):
+self.n_visible = n_visible
+self.n_hidden  = n_hidden
+# create a Theano random generator that gives symbolic random values
+theano_rng = RandomStreams()
+if shared_W != None and shared_b != None :
+self.W = shared_W
+self.b = shared_b
+else:
+# initial values for weights and biases
+# note : W' was written as `W_prime` and b' as `b_prime`
+# W is initialized with `initial_W` which is uniformely sampled
+# from -6./sqrt(n_visible+n_hidden) and 6./sqrt(n_hidden+n_visible)
+# the output of uniform if converted using asarray to dtype
+# theano.config.floatX so that the code is runable on GPU
+initial_W = numpy.asarray( numpy.random.uniform( \
+low = -numpy.sqrt(6./(n_hidden+n_visible)), \
+high = numpy.sqrt(6./(n_hidden+n_visible)), \
+size = (n_visible, n_hidden)), dtype = theano.config.floatX)
+initial_b       = numpy.zeros(n_hidden, dtype = theano.config.floatX)
+# theano shared variables for weights and biases
+self.W       = theano.shared(value = initial_W,       name = "W")
+self.b       = theano.shared(value = initial_b,       name = "b")
+initial_b_prime= numpy.zeros(n_visible)
+# tied weights, therefore W_prime is W transpose
+self.W_prime = self.W.T
+self.b_prime = theano.shared(value = initial_b_prime, name = "b'")
+# if no input is given, generate a variable representing the input
+if input == None :
+# we use a matrix because we expect a minibatch of several examples,
+# each example being a row
+self.x = T.dmatrix(name = 'input')
+else:
+self.x = input
+# Equation (1)
+# keep 90% of the inputs the same and zero-out randomly selected subset of 10% of the inputs
+# note : first argument of theano.rng.binomial is the shape(size) of
+#        random numbers that it should produce
+#        second argument is the number of trials
+#        third argument is the probability of success of any trial
+#
+#        this will produce an array of 0s and 1s where 1 has a
+#        probability of 1 - ``corruption_level`` and 0 with
+#        ``corruption_level``
+self.tilde_x  = theano_rng.binomial( self.x.shape,  1,  1 - corruption_level) * self.x
+# Equation (2)
+# note  : y is stored as an attribute of the class so that it can be
+#         used later when stacking dAs.
+self.y   = T.nnet.sigmoid(T.dot(self.tilde_x, self.W      ) + self.b)
+# Equation (3)
+self.z   = T.nnet.sigmoid(T.dot(self.y, self.W_prime) + self.b_prime)
+# Equation (4)
+# note : we sum over the size of a datapoint; if we are using minibatches,
+#        L will  be a vector, with one entry per example in minibatch
+#self.L = - T.sum( self.x*T.log(self.z) + (1-self.x)*T.log(1-self.z), axis=1 )
+#self.L = binary_cross_entropy(target=self.x, output=self.z, sum_axis=1)
+# bypassing z to avoid running to log(0)
+#self.z_a = T.dot(self.y, self.W_prime) + self.b_prime)
+#self.L = -T.sum( self.x * (T.log(1)-T.log(1+T.exp(-self.z_a))) \
+#                + (1.0-self.x) * (T.log(1)-T.log(1+T.exp(-self.z_a))), axis=1 )
+# I added this epsilon to avoid getting log(0) and 1/0 in grad
+# This means conceptually that there'd be no probability of 0, but that
+# doesn't seem to me as important (maybe I'm wrong?).
+eps = 0.00000001
+eps_1 = 1-eps
+self.L = - T.sum( self.x * T.log(eps + eps_1*self.z) \
++ (1-self.x)*T.log(eps + eps_1*(1-self.z)), axis=1 )
+# note : L is now a vector, where each element is the cross-entropy cost
+#        of the reconstruction of the corresponding example of the
+#        minibatch. We need to compute the average of all these to get
+#        the cost of the minibatch
+self.cost = T.mean(self.L)
+self.params = [ self.W, self.b, self.b_prime ]
+class SdA(object):
+def __init__(self, train_set_x, train_set_y, batch_size, n_ins,
+hidden_layers_sizes, n_outs,
+corruption_levels, rng, pretrain_lr, finetune_lr, input_divider=1.0):
+# Just to make sure those are not modified somewhere else afterwards
+hidden_layers_sizes = copy.deepcopy(hidden_layers_sizes)
+corruption_levels = copy.deepcopy(corruption_levels)
+update_locals(self, locals())
+self.layers             = []
+self.pretrain_functions = []
+self.params             = []
+# MODIF: added this so we also get the b_primes
+# (not used for finetuning... still using ".params")
+self.all_params         = []
+self.n_layers           = len(hidden_layers_sizes)
+print "Creating SdA with params:"
+print "batch_size", batch_size
+print "hidden_layers_sizes", hidden_layers_sizes
+print "corruption_levels", corruption_levels
+print "n_ins", n_ins
+print "n_outs", n_outs
+print "pretrain_lr", pretrain_lr
+print "finetune_lr", finetune_lr
+print "input_divider", input_divider
+print "----"
+self.shared_divider = theano.shared(numpy.asarray(input_divider, dtype=theano.config.floatX))
+if len(hidden_layers_sizes) < 1 :
+raiseException (' You must have at least one hidden layer ')
+# allocate symbolic variables for the data
+index   = T.lscalar()    # index to a [mini]batch
+self.x  = T.matrix('x')  # the data is presented as rasterized images
+self.y  = T.ivector('y') # the labels are presented as 1D vector of
+# [int] labels
+for i in xrange( self.n_layers ):
+# construct the sigmoidal layer
+# the size of the input is either the number of hidden units of
+# the layer below or the input size if we are on the first layer
+if i == 0 :
+input_size = n_ins
+else:
+input_size = hidden_layers_sizes[i-1]
+# the input to this layer is either the activation of the hidden
+# layer below or the input of the SdA if you are on the first
+# layer
+if i == 0 :
+layer_input = self.x
+else:
+layer_input = self.layers[-1].output
+layer = SigmoidalLayer(rng, layer_input, input_size,
+hidden_layers_sizes[i] )
+# add the layer to the
+self.layers += [layer]
+self.params += layer.params
+# Construct a denoising autoencoder that shared weights with this
+# layer
+dA_layer = dA(input_size, hidden_layers_sizes[i], \
+corruption_level = corruption_levels[0],\
+input = layer_input, \
+shared_W = layer.W, shared_b = layer.b)
+self.all_params += dA_layer.params
+# Construct a function that trains this dA
+# compute gradients of layer parameters
+gparams = T.grad(dA_layer.cost, dA_layer.params)
+# compute the list of updates
+updates = {}
+for param, gparam in zip(dA_layer.params, gparams):
+updates[param] = param - gparam * pretrain_lr
+# create a function that trains the dA
+update_fn = theano.function([index], dA_layer.cost, \
+updates = updates,
+givens = {
+self.x : train_set_x[index*batch_size:(index+1)*batch_size] / self.shared_divider})
+# collect this function into a list
+self.pretrain_functions += [update_fn]
+# We now need to add a logistic layer on top of the MLP
+self.logLayer = LogisticRegression(\
+input = self.layers[-1].output,\
+n_in = hidden_layers_sizes[-1], n_out = n_outs)
+self.params += self.logLayer.params
+self.all_params += self.logLayer.params
+# construct a function that implements one step of finetunining
+# compute the cost, defined as the negative log likelihood
+cost = self.logLayer.negative_log_likelihood(self.y)
+# compute the gradients with respect to the model parameters
+gparams = T.grad(cost, self.params)
+# compute list of updates
+updates = {}
+for param,gparam in zip(self.params, gparams):
+updates[param] = param - gparam*finetune_lr
+self.finetune = theano.function([index], cost,
+updates = updates,
+givens = {
+self.x : train_set_x[index*batch_size:(index+1)*batch_size]/self.shared_divider,
+self.y : train_set_y[index*batch_size:(index+1)*batch_size]} )
+# symbolic variable that points to the number of errors made on the
+# minibatch given by self.x and self.y
+self.errors = self.logLayer.errors(self.y)
+if __name__ == '__main__':
+import sys
+args = sys.argv[1:]

Mercurial > ift6266

comparison deep/stacked_dae/old/stacked_dae.py @ 265:c8fe09a65039