Mercurial > pylearn
view nnet_ops.py @ 437:2d8490d76b3e
added two methods to make_test_datasets
author | Olivier Breuleux <breuleuo@iro.umontreal.ca> |
---|---|
date | Wed, 06 Aug 2008 19:39:36 -0400 |
parents | 43d9aa93934e |
children | 18dbc1c11647 |
line wrap: on
line source
## This file contain ops that are not currently integrated in the core of threano. ## Not all of those ops have been thoroughly tested. import theano from theano import tensor, scalar import numpy ############ # # SCALAR OPS # class ScalarSigmoid(scalar.UnaryScalarOp): @staticmethod def st_impl(x): if x < -30.0: return 0.0 if x > 30.0: return 1.0 return 1.0 / (1.0 + numpy.exp(-x)) def impl(self, x): return ScalarSigmoid.st_impl(x) def grad(self, (x,), (gz,)): y = scalar_sigmoid(x) return [gz * y * (1.0 - y)] def c_code(self, node, name, (x,), (z,), sub): if node.inputs[0].type in [scalar.float32, scalar.float64]: return """%(z)s = %(x)s < -30.0 ? 0.0 : %(x)s > 30.0 ? 1.0 : 1.0 /(1.0+exp(-%(x)s));""" % locals() raise NotImplementedError('only floatingpoint is implemented') scalar_sigmoid = ScalarSigmoid(scalar.upgrade_to_float, name='scalar_sigmoid') sigmoid = tensor.Elemwise(scalar_sigmoid, name='sigmoid') class ScalarSoftplus(scalar.UnaryScalarOp): @staticmethod def static_impl(x): if x < -30.0: return 0.0 if x > 30.0: return x return numpy.log1p(numpy.exp(x)) def impl(self, x): return ScalarSoftplus.static_impl(x) def grad(self, (x,), (gz,)): return [gz * scalar_sigmoid(x)] def c_code(self, node, name, (x,), (z,), sub): if node.inputs[0].type in [scalar.float32, scalar.float64]: return """%(z)s = %(x)s < -30.0 ? 0.0 : %(x)s > 30.0 ? %(x)s : log1p(exp(%(x)s));""" % locals() raise NotImplementedError('only floating point x is implemented') scalar_softplus = ScalarSoftplus(scalar.upgrade_to_float, name='scalar_softplus') softplus = tensor.Elemwise(scalar_softplus, name='softplus') ############ # # TENSOR OPS # class CrossentropySoftmax1HotWithBias(theano.Op): """A special compound L{Op} for the output of neural-net classifiers. @type x: is a matrix of floats (32 or 64) @type b: is a [row] vector of floats (32 or 64), length is number of cols in x @type y_idx: a [column] vector of int (32 or 64), length is number of rows in x @precondition: every entry in y_idx is a valid (non-negative) column index into x This L{Op} has two outputs: - KL(softmax(x+b), y) - softmax(x+b) softmax(x[i]) is the i'th distribution over len(x[i]) options y_idx[i] is an integer index, encoding a 1-hot distribution. In practice, when we're trying to do classification, we have one row in x and y_idx per example, and y[i] is the index of the (correct) class of the i'th example. """ nin=3 nout=2 def __init__(self, **kwargs): theano.Op.__init__(self, **kwargs) def make_node(self, x, b, y_idx): x = tensor.as_tensor(x) b = tensor.as_tensor(b) y_idx = tensor.as_tensor(y_idx) if x.type.ndim != 2 \ or x.type.dtype not in ['float32', 'float64']: raise ValueError('x must be 2-d tensor of floats') if b.type.ndim != 1 \ or x.type.dtype not in ['float32', 'float64']: raise ValueError('b must be 1-d tensor of floats') if y_idx.type.ndim != 1 \ or y_idx.type.dtype not in ['int8', 'int16', 'int32', 'int64']: raise ValueError('y_idx must be 1-d tensor of ints') # TODO: Is this correct? It used to be y, not y_idx nll = tensor.Tensor(x.type.dtype, y_idx.type.broadcastable).make_result() # nll = Tensor(x.dtype, y.broadcastable) sm = x.type.make_result() return theano.Apply(self, [x, b, y_idx], [nll, sm]) def perform(self, node, input_storage, output_storage): x, b, y_idx = input_storage if b.shape[0] != x.shape[1]: raise ValueError('b must have same number of columns as x') if y_idx.shape[0] != x.shape[0]: raise ValueError('y_idx must have same number of rows as x') sm = numpy.zeros_like(x) # softmax nll = numpy.zeros(x.shape[0]) #nll(y | softmax(x)) for i in xrange(sm.shape[0]): row = x[i] + b sm[i] = numpy.exp(row - numpy.max(row)) #softmax sm[i] *= 1.0 / numpy.sum(sm[i]) #vector scale nll[i] = -numpy.log( sm[i, y_idx[i]]) #cross-entropy output_storage[0][0] = nll output_storage[1][0] = sm def grad(self, (x, b, y_idx), (g_nll, g_sm)): if g_sm is not None: raise NotImplementedError() nll, sm = crossentropy_softmax_1hot_with_bias(x, b, y_idx) dx = CrossentropySoftmax1HotWithBiasDx()(g_nll, sm, y_idx) db = tensor.sum(dx, axis = [0]) return dx, db, None def c_headers(self): return ['<iostream>'] def c_code(self, node, name, (x, b, y_idx), (nll, sm), sub): # this implementation was lifted from # /u/bergstrj/cvs/bergstrj/src/feb07/nn.cxx #TODO: put this into a templated function, in the support code #TODO: declare the max of each row as an Op output #TODO: set error messages for failures in this code #TODO: use this to accept float32 and int32: node.inputs[0].type.dtype_specs()[1] y_idx_type = node.inputs[2].type.dtype_specs()[1] return """ npy_intp* Nx = %(x)s->dimensions; if (%(x)s->nd != 2) { PyErr_SetString(PyExc_ValueError, "a not 2d tensor"); %(fail)s; } if (%(b)s->nd != 1) { PyErr_SetString(PyExc_ValueError, "b not 1d tensor"); %(fail)s; } if (%(y_idx)s->nd != 1) { PyErr_SetString(PyExc_ValueError, "y_idx not 1d tensor"); %(fail)s; } if (%(x)s->descr->type_num != PyArray_DOUBLE) { PyErr_SetString(PyExc_TypeError, "a not float64"); %(fail)s; } if (%(b)s->descr->type_num != PyArray_DOUBLE) { PyErr_SetString(PyExc_TypeError, "b not float64"); %(fail)s; } if ((%(y_idx)s->descr->type_num != PyArray_INT64) && (%(y_idx)s->descr->type_num != PyArray_INT32) && (%(y_idx)s->descr->type_num != PyArray_INT16) && (%(y_idx)s->descr->type_num != PyArray_INT8)) { PyErr_SetString(PyExc_TypeError, "y_idx not int8, int16, int32, or int64"); %(fail)s; } if ((%(x)s->dimensions[1] != %(b)s->dimensions[0]) || (%(x)s->dimensions[0] != %(y_idx)s->dimensions[0])) { PyErr_SetString(PyExc_ValueError, "dimension mismatch in arguments"); %(fail)s; } if ((NULL == %(nll)s) //initial condition || (%(nll)s->dimensions[0] != %(y_idx)s->dimensions[0])) { if (NULL != %(nll)s) Py_XDECREF(%(nll)s); %(nll)s = (PyArrayObject*)PyArray_SimpleNew(1, PyArray_DIMS(%(y_idx)s), type_num_%(x)s); if(!%(nll)s) { PyErr_SetString(PyExc_MemoryError, "failed to alloc nll output"); %(fail)s; } } if ((NULL == %(sm)s) || (%(sm)s->dimensions[0] != %(x)s->dimensions[0]) || (%(sm)s->dimensions[1] != %(x)s->dimensions[1])) { if (NULL != %(sm)s) Py_XDECREF(%(sm)s); %(sm)s = (PyArrayObject*)PyArray_SimpleNew(2, PyArray_DIMS(%(x)s), type_num_%(x)s); if(!%(sm)s) { // The normal cleanup code will take care of %(nll)s // Py_XDECREF(%(nll)s); %(nll)s=NULL; PyErr_SetString(PyExc_MemoryError, "failed to alloc sm output"); %(fail)s } } for (size_t i = 0; i < Nx[0]; ++i) { size_t j; double sum = 0.0; bool discount_max = false; const double* __restrict__ x_i = (double*)(%(x)s->data + %(x)s->strides[0] * i); const double* __restrict__ b_i = (double*)(%(b)s->data); const %(y_idx_type)s y_i = ((%(y_idx_type)s*)(%(y_idx)s->data + %(y_idx)s->strides[0] * i))[0]; double* __restrict__ sm_i = (double*)(%(sm)s->data + %(sm)s->strides[0] * i); double* __restrict__ nll_i = (double*)(%(nll)s->data + %(nll)s->strides[0] * i); npy_intp Sx = %(x)s->strides[1]/sizeof(double); npy_intp Sb = %(b)s->strides[0]/sizeof(double); npy_intp Ssm = %(sm)s->strides[1]/sizeof(double); size_t row_max_j=0; double row_max = x_i[0] + b_i[0]; //try to compute sum and sm the easy way for (j = 0; j < Nx[1]; ++j) { double row_ij = x_i[j * Sx] + b_i[j * Sb]; row_max_j = (row_ij > row_max) ? j : row_max_j; row_max = (row_ij > row_max) ? row_ij : row_max; double sm_ij = exp(row_ij); sum += sm_ij; sm_i[j * Ssm] = sm_ij; } if ((0.0 == sum) || (isinf(sum))) { //our cheap trick didn't work... try again and do it better. discount_max = true; sum = 0.0; //reset sum and recompute.... for (j = 0; j < Nx[1]; ++j) { double row_ij = x_i[j * Sx] + b_i[j * Sb]; double sm_ij = exp(row_ij - row_max); sum += sm_ij; sm_i[j * Ssm] = sm_ij; } if ( (0.0 == sum) || (isinf(sum))) { //that was our best... %(fail)s; } //if we still can't sum it up, we're screwed. //So far, this assertion has never failed... } //cblas_dscal(x.N, 1.0 / sum, &mat_at(s,i,0), s.n); double sum_inv = 1.0 / sum; for (j = 0; j < Nx[1]; ++j) { sm_i[j * Ssm] *= sum_inv; } if (y_i >= Nx[1]) { %(fail)s; } nll_i[0] = - x_i[y_i*Sx] - b_i[y_i*Sb] + (discount_max ? row_max : 0.0) + log(sum); //mat_at(y,i,0) = -log( mat_at(s,i,t[i])); //less accurate? //mat_at(y,i,0) = - mat_at(x,i,t[i]) - mat_at(b,0,t[i]) + (discount_max ? maxi : 0.0) + log(sum); } """ % dict(locals(), **sub) crossentropy_softmax_1hot_with_bias = CrossentropySoftmax1HotWithBias() class CrossentropySoftmax1HotWithBiasDx (theano.Op): nin=3 nout=1 """Gradient wrt x of the CrossentropySoftmax1Hot Op""" def __init__(self, **kwargs): theano.Op.__init__(self,**kwargs) def make_node(self, dy, sm, y_idx,**kwargs): dy = tensor.as_tensor(dy) sm = tensor.as_tensor(sm) y_idx = tensor.as_tensor(y_idx) return theano.Apply(self, [dy, sm, y_idx],[sm.type.make_result()]) def perform(self, node, input_storage, output_storage): dy,sm,y_idx = input_storage dx = numpy.zeros_like(sm) for i in xrange(sm.shape[0]): dx[i] = dy[i] * sm[i] #vector scale dx[i, y_idx[i]] -= dy[i] #scalar decrement output_storage[0][0] = dx def grad(self, *args): raise NotImplementedError() def c_code(self, node, name, (dnll, sm, y_idx), (dx,), sub): y_idx_type = node.inputs[2].type.dtype_specs()[1] return """ if ((%(dnll)s->descr->type_num != PyArray_DOUBLE) || (%(sm)s->descr->type_num != PyArray_DOUBLE) ) { PyErr_SetString(PyExc_TypeError, "types should be float64, float64, int64"); %(fail)s; } if ((%(y_idx)s->descr->type_num != PyArray_INT64) && (%(y_idx)s->descr->type_num != PyArray_INT32) && (%(y_idx)s->descr->type_num != PyArray_INT16) && (%(y_idx)s->descr->type_num != PyArray_INT8)) { PyErr_SetString(PyExc_TypeError, "y_idx not int8, int16, int32, or int64"); %(fail)s; } if ((%(dnll)s->nd != 1) || (%(sm)s->nd != 2) || (%(y_idx)s->nd != 1)) { PyErr_SetString(PyExc_ValueError, "rank error"); %(fail)s; } if ((%(dnll)s->dimensions[0] != %(sm)s->dimensions[0]) || (%(dnll)s->dimensions[0] != %(y_idx)s->dimensions[0])) { PyErr_SetString(PyExc_ValueError, "dimension mismatch"); %(fail)s; } if ((NULL == %(dx)s) || (%(dx)s->dimensions[0] != %(sm)s->dimensions[0]) || (%(dx)s->dimensions[1] != %(sm)s->dimensions[1])) { if (NULL != %(dx)s) Py_XDECREF(%(dx)s); %(dx)s = (PyArrayObject*)PyArray_SimpleNew(2, PyArray_DIMS(%(sm)s), type_num_%(sm)s); if(!%(dx)s) { PyErr_SetString(PyExc_MemoryError, "failed to alloc dx output"); %(fail)s } } for (size_t i = 0; i < %(dx)s->dimensions[0]; ++i) { const double dnll_i = ((double*)(%(dnll)s->data + %(dnll)s->strides[0] * i))[0]; const %(y_idx_type)s y_i = ((%(y_idx_type)s*)(%(y_idx)s->data + %(y_idx)s->strides[0] * i))[0]; const double* __restrict__ sm_i = (double*)(%(sm)s->data + %(sm)s->strides[0] * i); npy_intp Ssm = %(sm)s->strides[1]/sizeof(double); double* __restrict__ dx_i = (double*)(%(dx)s->data + %(dx)s->strides[0] * i); npy_intp Sdx = %(dx)s->strides[1]/sizeof(double); for (size_t j = 0; j < %(dx)s->dimensions[1]; ++j) { dx_i[j * Sdx] = dnll_i * sm_i[j * Ssm]; } if (y_i >= %(dx)s->dimensions[1]) { %(fail)s; } dx_i[y_i * Sdx] -= dnll_i; } """ % dict(locals(), **sub) def crossentropy_softmax_1hot(x, y_idx, **kwargs): b = tensor.zeros_like(x[0,:]) return crossentropy_softmax_1hot_with_bias(x, b, y_idx, **kwargs) def binary_crossentropy(output, target): """ Compute the crossentropy of binary output wrt binary target. @note: We do not sum, crossentropy is computed by component. @todo: Rewrite as a scalar, and then broadcast to tensor. """ return -(target * tensor.log(output) + (1 - target) * tensor.log(1 - output)) class Prepend_scalar_constant_to_each_row(theano.Op): def __init__(self, val = 0): if isinstance(val, float): val = scalar.constant(val) self.val = val def make_node(self, mat): #check type of input if not isinstance(mat,theano.Result) or not mat.type==tensor.matrix().type: raise TypeError("Expected a matrix as input") x = tensor.as_tensor(mat) y = tensor.as_tensor(self.val) if x.type.dtype != y.type.dtype: TypeError("the value to prepend don't have the same type as the matrix") node = theano.Apply(op=self, inputs=[mat], outputs=[tensor.matrix()]) return node def perform(self, node, (mat, ), (output, )): new_shape=(mat.shape[0],mat.shape[1]+1) if output[0] == None: output[0]=numpy.empty(new_shape,dtype=mat.dtype) out=output[0] else: if output[0].shape!=new_shape: try: output[0].resize(new_shape) except: output[0]=numpy.empty(new_shape, dtype=mat.dtype) out=output[0] out[:,0].fill(self.val.data) out[:,1:]=mat def grad(self, (mat,), (goutput,)): return goutput[:,1:] class Prepend_scalar_to_each_row(theano.Op): def make_node(self, val, mat): #check type of input if isinstance(val, float): val = scalar.constant(val) if not isinstance(mat,theano.Result) or not mat.type==tensor.matrix().type: raise TypeError("Expected a matrix as input") x = tensor.as_tensor(mat) y = tensor.as_tensor(val) if x.type.dtype != y.type.dtype: TypeError("the value to prepend don't have the same type as the matrix") node = theano.Apply(op=self, inputs=[val,mat], outputs=[tensor.matrix()]) return node def perform(self, node, (val,mat), (output, )): new_shape=(mat.shape[0],mat.shape[1]+1) if output[0] == None: output[0]=numpy.empty(new_shape,dtype=mat.dtype) out=output[0] else: if output[0].shape!=new_shape: try: output[0].resize(new_shape) except: output[0]=numpy.empty(new_shape, dtype=mat.dtype) out=output[0] out[:,0].fill(val) out[:,1:]=mat def grad(self, (val, mat), (goutput,)): return goutput[:,0], goutput[:,1:] prepend_scalar_to_each_row = Prepend_scalar_to_each_row() prepend_0_to_each_row = Prepend_scalar_constant_to_each_row(0.) prepend_1_to_each_row = Prepend_scalar_constant_to_each_row(1.) class solve(theano.Op): """ Find the solution to the linear equation Ax=b, where A is a 2d matrix and b is a 1d or 2d matrix. It use numpy.solve to find the solution. """ def make_node(self, A, b): if not isinstance(A, theano.Result) or not A.type==tensor.matrix().type: raise TypeError("We expected that A had a matrix type") if not isinstance(B, theano.Result) or not B.type==tensor.matrix().type: raise TypeError("We expected that B had a matrix type") node = theano.Apply(op=self, inputs=[A, B], outputs=[tensor.matrix()]) return node def perform(self, node, (A, B), (output, )): ret=numpy.solve(A,B) output[0]=ret def grad(self, (theta, A, B), (gtheta,)): raise NotImplementedError()