Lasagne Backend Support

.gitignore

@@ -25,7 +25,6 @@ var/
 *.egg
 
 # Machine Learning
-Lasagne/
 nolearn/
 scikit-learn/
 

sknn/__init__.py

@@ -2,7 +2,7 @@
 from __future__ import (absolute_import, unicode_literals, print_function)
 
 __author__ = 'alexjc, ssamot'
-__version__ = '0.3'
+__version__ = '0.4'
 
 
 import os

sknn/backend/__init__.py

@@ -21,5 +21,5 @@ def __init__(self, _):
 # Automatically import the recommended backend if none was manually imported.
 def setup():
     if name == None:
-        from . import pylearn2
-    assert name is not None
+        from . import pylearn2 
+    assert name is not None, "No backend for module sknn was imported."

sknn/backend/lasagne/__init__.py

@@ -0,0 +1,9 @@
+# -*- coding: utf-8 -*-
+from __future__ import (absolute_import, unicode_literals, print_function)
+
+from ... import backend
+from .mlp import MultiLayerPerceptronBackend
+
+# Register this implementation as the MLP backend.
+backend.MultiLayerPerceptronBackend = MultiLayerPerceptronBackend
+backend.name = 'lasagne'

sknn/backend/lasagne/mlp.py

@@ -0,0 +1,275 @@
+# -*- coding: utf-8 -*-
+from __future__ import (absolute_import, unicode_literals, print_function)
+
+__all__ = ['MultiLayerPerceptronBackend']
+
+import os
+import sys
+import math
+import time
+import logging
+import itertools
+
+log = logging.getLogger('sknn')
+
+
+import numpy
+import theano
+import sklearn.base
+import sklearn.pipeline
+import sklearn.preprocessing
+import sklearn.cross_validation
+
+import theano.tensor as T
+import lasagne.layers
+import lasagne.nonlinearities as nl
+
+from ..base import BaseBackend
+from ...nn import Layer, Convolution, ansi
+
+
+class MultiLayerPerceptronBackend(BaseBackend):
+    """
+    Abstract base class for wrapping the multi-layer perceptron functionality
+    from Lasagne.
+    """
+
+    def __init__(self, spec):
+        super(MultiLayerPerceptronBackend, self).__init__(spec)
+        self.mlp = None
+        self.f = None
+        self.trainer = None
+        self.cost = None
+
+    def _create_mlp_trainer(self, params):
+        # Aggregate all regularization parameters into common dictionaries.
+        layer_decay = {}
+        if self.regularize in ('L1', 'L2') or any(l.weight_decay for l in self.layers):
+            wd = self.weight_decay or 0.0001
+            for l in self.layers:
+                layer_decay[l.name] = l.weight_decay or wd
+        assert len(layer_decay) == 0 or self.regularize in ('L1', 'L2', None)
+
+        if len(layer_decay) > 0:
+            if self.regularize is None:
+                self.regularize = 'L2'
+            penalty = getattr(lasagne.regularization, self.regularize.lower())
+            regularize = lasagne.regularization.apply_penalty
+            self.cost = sum(layer_decay[s.name] * regularize(l.get_params(tags={'regularizable': True}), penalty)
+                                for s, l in zip(self.layers, self.mlp))
+
+        cost_functions = {'mse': 'squared_error', 'mcc': 'categorical_crossentropy'}
+        loss_type = self.loss_type or ('mcc' if self.is_classifier else 'mse')
+        assert loss_type in cost_functions,\
+                    "Loss type `%s` not supported by Lasagne backend." % loss_type
+        cost_fn = getattr(lasagne.objectives, cost_functions[loss_type])
+        cost_eval = cost_fn(self.symbol_output, self.tensor_output).mean()
+        if self.cost is not None:
+            cost_eval = cost_eval * self.cost
+        return self._create_trainer(params, cost_eval)
+
+    def _create_trainer(self, params, cost):
+        if self.learning_rule in ('sgd', 'adagrad', 'adadelta', 'rmsprop', 'adam'):
+            lr = getattr(lasagne.updates, self.learning_rule)
+            self._learning_rule = lr(cost, params, learning_rate=self.learning_rate)
+        elif self.learning_rule in ('momentum', 'nesterov'):
+            lasagne.updates.nesterov = lasagne.updates.nesterov_momentum
+            lr = getattr(lasagne.updates, self.learning_rule)
+            self._learning_rule = lr(cost, params, learning_rate=self.learning_rate, momentum=self.learning_momentum)
+        else:
+            raise NotImplementedError(
+                "Learning rule type `%s` is not supported." % self.learning_rule)
+
+        return theano.function([self.tensor_input, self.tensor_output], cost,
+                               updates=self._learning_rule,
+                               allow_input_downcast=True)
+
+    def _get_activation(self, l):        
+        nonlinearities = {'Rectifier': nl.rectify,
+                          'Sigmoid': nl.sigmoid,
+                          'Tanh': nl.tanh,
+                          'Softmax': nl.softmax,
+                          'Linear': nl.linear}
+
+        assert l.type in nonlinearities,\
+            "Layer type `%s` is not supported for `%s`." % (l.type, l.name)
+        return nonlinearities[l.type]
+
+    def _create_convolution_layer(self, name, layer, network):
+        self._check_layer(layer,
+                          required=['channels', 'kernel_shape'],
+                          optional=['kernel_stride', 'border_mode', 'pool_shape', 'pool_type'])
+
+        network = lasagne.layers.Conv2DLayer(
+                        network,
+                        num_filters=layer.channels,
+                        filter_size=layer.kernel_shape,
+                        stride=layer.kernel_stride,
+                        pad=layer.border_mode,
+                        nonlinearity=self._get_activation(layer))
+
+        if layer.pool_shape != (1, 1):
+            network = lasagne.layers.Pool2DLayer(
+                        network,
+                        pool_size=layer.pool_shape,
+                        stride=layer.pool_shape)
+
+        return network
+
+    def _create_layer(self, name, layer, network):
+        dropout = layer.dropout or self.dropout_rate
+        if dropout is not None:
+            network = lasagne.layers.dropout(network, dropout)
+
+        if isinstance(layer, Convolution):
+            return self._create_convolution_layer(name, layer, network)
+
+        self._check_layer(layer, required=['units'])
+        return lasagne.layers.DenseLayer(network,
+                                         num_units=layer.units,
+                                         nonlinearity=self._get_activation(layer))
+
+    def _create_mlp(self, X):
+        self.tensor_input = T.tensor4('X') if self.is_convolution else T.matrix('X')
+        self.tensor_output = T.matrix('y')
+
+        lasagne.random.get_rng().seed(self.random_state)
+
+        shape = list(X.shape)
+        network = lasagne.layers.InputLayer([None]+shape[1:], self.tensor_input)
+
+        # Create the layers one by one, connecting to previous.
+        self.mlp = []
+        for i, layer in enumerate(self.layers):
+            network = self._create_layer(layer.name, layer, network)
+            self.mlp.append(network)
+
+        log.info(
+            "Initializing neural network with %i layers, %i inputs and %i outputs.",
+            len(self.layers), self.unit_counts[0], self.layers[-1].units)
+
+        for l, p, count in zip(self.layers, self.mlp, self.unit_counts[1:]):
+            space = p.output_shape
+            if isinstance(l, Convolution):
+                log.debug("  - Convl: {}{: <10}{} Output: {}{: <10}{} Channels: {}{}{}".format(
+                    ansi.BOLD, l.type, ansi.ENDC,
+                    ansi.BOLD, repr(space[2:]), ansi.ENDC,
+                    ansi.BOLD, space[1], ansi.ENDC))
+
+                # NOTE: Numbers don't match up exactly for pooling; one off. The logic is convoluted!
+                # assert count == numpy.product(space.shape) * space.num_channels,\
+                #     "Mismatch in the calculated number of convolution layer outputs."
+            else:
+                log.debug("  - Dense: {}{: <10}{} Units:  {}{: <4}{}".format(
+                    ansi.BOLD, l.type, ansi.ENDC, ansi.BOLD, l.units, ansi.ENDC))
+                assert count == space[1],\
+                    "Mismatch in the calculated number of dense layer outputs."
+
+        if self.weights is not None:
+            l  = min(len(self.weights), len(self.mlp))
+            log.info("Reloading parameters for %i layer weights and biases." % (l,))
+            self._array_to_mlp(self.weights, self.mlp)
+            self.weights = None
+
+        log.debug("")
+
+        self.symbol_output = lasagne.layers.get_output(network, deterministic=True)
+        self.f = theano.function([self.tensor_input], self.symbol_output, allow_input_downcast=True)
+
+    def _initialize_impl(self, X, y=None):
+        if self.is_convolution:
+            X = numpy.transpose(X, (0, 3, 1, 2))
+
+        if self.mlp is None:            
+            self._create_mlp(X)
+
+        # Can do partial initialization when predicting, no trainer needed.
+        if y is None:
+            return
+
+        if self.valid_size > 0.0:
+            assert self.valid_set is None, "Can't specify valid_size and valid_set together."
+            X, X_v, y, y_v = sklearn.cross_validation.train_test_split(
+                                X, y,
+                                test_size=self.valid_size,
+                                random_state=self.random_state)
+            self.valid_set = X_v, y_v
+
+        params = []
+        for spec, mlp_layer in zip(self.layers, self.mlp):
+            if spec.frozen: continue
+            params.extend(mlp_layer.get_params())
+
+        self.trainer = self._create_mlp_trainer(params)
+        return X, y
+
+    def _predict_impl(self, X):
+        if not self.is_initialized:
+            self._initialize_impl(X)
+
+        if self.is_convolution:
+            X = numpy.transpose(X, (0, 3, 1, 2))
+        return self.f(X)
+
+    def _iterate_data(self, X, y, batch_size, shuffle=False):
+        def cast(array):
+            if type(array) != numpy.ndarray:
+                array = array.todense()
+            return array.astype(theano.config.floatX)
+
+        total_size = X.shape[0]
+        indices = numpy.arange(total_size)
+        if shuffle:
+            numpy.random.shuffle(indices)
+
+        for start_idx in range(0, total_size - batch_size + 1, batch_size):
+            excerpt = indices[start_idx:start_idx + batch_size]
+            Xb, yb = cast(X[excerpt]), cast(y[excerpt])
+            if self.mutator is not None:
+                for x, _ in zip(Xb, yb):
+                    self.mutator(x)
+            yield Xb, yb
+
+    def _train_impl(self, X, y):
+        loss, batches = 0.0, 0
+        for Xb, yb in self._iterate_data(X, y, self.batch_size, shuffle=True):
+            loss += self.trainer(Xb, yb)
+            batches += 1
+        return loss / batches
+
+    def _valid_impl(self, X, y):
+        loss, batches = 0.0, 0
+        for Xb, yb in self._iterate_data(X, y, self.batch_size, shuffle=True):
+            ys = self.f(Xb)
+            loss += ((ys - yb) ** 2.0).mean()
+            batches += 1
+        return loss / batches
+
+    @property
+    def is_initialized(self):
+        """Check if the neural network was setup already.
+        """
+        return not (self.f is None)
+
+    def _mlp_get_params(self, layer):
+        while not hasattr(layer, 'W') and not hasattr(layer, 'b'):
+            layer = layer.input_layer
+        return (layer.W.get_value(), layer.b.get_value())
+
+    def _mlp_to_array(self):
+        return [self._mlp_get_params(l) for l in self.mlp]
+
+    def _array_to_mlp(self, array, nn):
+        for layer, (weights, biases) in zip(nn, array):
+            while not hasattr(layer, 'W') and not hasattr(layer, 'b'):
+                layer = layer.input_layer
+
+            ws = tuple(layer.W.shape.eval())
+            assert ws == weights.shape, "Layer weights shape mismatch: %r != %r" %\
+                                        (ws, weights.shape)
+            layer.W.set_value(weights)
+
+            bs = tuple(layer.b.shape.eval())
+            assert bs == biases.shape, "Layer biases shape mismatch: %r != %r" %\
+                                       (bs, biases.shape)
+            layer.b.set_value(biases)

sknn/backend/pylearn2/__init__.py

@@ -1,6 +1,18 @@
 # -*- coding: utf-8 -*-
 from __future__ import (absolute_import, unicode_literals, print_function)
 
+from ...nn import ansi
+
+
+import warnings
+warnings.warn(ansi.YELLOW + """\n
+The PyLearn2 backend is deprecated; the next release will switch to Lasagne by default.
+
+Test the change using the following at the top of your script:
+> from sknn.backend import lasagne
+""" + ansi.ENDC, category=UserWarning)
+
+
 from ... import backend
 from .mlp import MultiLayerPerceptronBackend
 from .ae import AutoEncoderBackend

sknn/backend/pylearn2/dataset.py

@@ -103,7 +103,7 @@ def _mutate_fn(self, array):
         array = self._conv_fn(array)
         if self.mutator is not None:
             for i in range(array.shape[0]):
-                self.mutator(array[i])
+                array[i] = self.mutator(array[i])
         return array
 
     @functools.wraps(dataset.Dataset.iterator)
@@ -160,17 +160,3 @@ def iterator(self, **kwargs):
         if self.mutator is not None:
             bit._convert[0] = self._conv_fn
         return bit
-
-"""
-OriginalDatasetIterator = iteration.FiniteDatasetIterator
-
-def create_finite_iterator(*args, **kwargs):
-    print('create_finite_iterator', kwargs['convert'])
-    def conv_fn(x):
-        return x + 0.01
-    kwargs['convert'] = [conv_fn, None]
-    return OriginalDatasetIterator(*args, **kwargs)
-    # convert=convert)
-
-datasets.dense_design_matrix.FiniteDatasetIterator = create_finite_iterator
-"""

sknn/backend/pylearn2/mlp.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import (absolute_import, unicode_literals, print_function)
 
-__all__ = ['Regressor', 'Classifier', 'Layer', 'Convolution']
+__all__ = ['MultiLayerPerceptronBackend']
 
 import os
 import sys
@@ -270,7 +270,10 @@ def _train_impl(self, X, y):
             X = self.ds.view_converter.topo_view_to_design_mat(X)
         self.ds.X, self.ds.y = X, y
 
-        self._train_layer(self.trainer, self.mlp, self.ds)
+        return self._train_layer(self.trainer, self.mlp, self.ds)
+
+    def _valid_impl(self, X, y):
+        return self._valid_layer(self.mlp)
 
     @property
     def is_initialized(self):