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-rw-r--r--mohammad/LICENSE201
-rw-r--r--mohammad/README.md33
-rw-r--r--mohammad/ctc_cost.py206
-rw-r--r--mohammad/ctc_test_data.pklbin0 -> 2080084 bytes
-rw-r--r--mohammad/test_ctc.py135
5 files changed, 575 insertions, 0 deletions
diff --git a/mohammad/LICENSE b/mohammad/LICENSE
new file mode 100644
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+++ b/mohammad/LICENSE
@@ -0,0 +1,201 @@
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diff --git a/mohammad/README.md b/mohammad/README.md
new file mode 100644
index 0000000..8c553c3
--- /dev/null
+++ b/mohammad/README.md
@@ -0,0 +1,33 @@
+CTC-Connectionist Temporal Classification
+=========================================
+
+-CTC cost is implemented in pure [Theano](https://github.com/Theano/Theano).
+
+-Supports mini-batch.
+
+-Supports both normal- and log-scale.
+
+-"apple" problem (two same consecutive labels) is solved.
+
+-Test file is implemented using [Blocks](https://github.com/bartvm/blocks).
+
+
+
+
+Reference
+=========
+Graves, Alex, et al. "Connectionist temporal classification: labelling unsegmented sequence data with recurrent neural networks." Proceedings of the 23rd international conference on Machine learning. ACM, 2006.
+
+
+Credits
+=======
+Theano implementation of CTC by [Shawn Tan](https://github.com/shawntan/rnn-experiment/)
+
+Theano implementation of CTC by [Rakesh Var](https://github.com/rakeshvar/rnn_ctc)
+
+
+Special thanks to
+=================
+[Kyle Kastner](https://github.com/kastnerkyle)
+
+Pascal Lambdin
diff --git a/mohammad/ctc_cost.py b/mohammad/ctc_cost.py
new file mode 100644
index 0000000..979ed93
--- /dev/null
+++ b/mohammad/ctc_cost.py
@@ -0,0 +1,206 @@
+"""
+CTC-Connectionist Temporal Classification
+
+Code provided by Mohammad Pezeshki - May. 2015 -
+Montreal Institute for Learning Algorithms
+
+Referece: Graves, Alex, et al. "Connectionist temporal classification:
+labelling unsegmented sequence data with recurrent neural networks."
+Proceedings of the 23rd international conference on Machine learning.
+ACM, 2006.
+
+Credits: Shawn Tan, Rakesh Var
+
+This code is distributed without any warranty, express or implied.
+"""
+
+import theano
+from theano import tensor
+
+floatX = theano.config.floatX
+
+
+# T: INPUT_SEQUENCE_LENGTH
+# B: BATCH_SIZE
+# L: OUTPUT_SEQUENCE_LENGTH
+# C: NUM_CLASSES
+class CTC(object):
+ """Connectionist Temporal Classification
+ y_hat : T x B x C+1
+ y : L x B
+ y_hat_mask : T x B
+ y_mask : L x B
+ """
+ @staticmethod
+ def add_blanks(y, blank_symbol, y_mask=None):
+ """Add blanks to a matrix and updates mask
+
+ Input shape: L x B
+ Output shape: 2L+1 x B
+
+ """
+ # for y
+ y_extended = y.T.dimshuffle(0, 1, 'x')
+ blanks = tensor.zeros_like(y_extended) + blank_symbol
+ concat = tensor.concatenate([y_extended, blanks], axis=2)
+ res = concat.reshape((concat.shape[0],
+ concat.shape[1] * concat.shape[2])).T
+ begining_blanks = tensor.zeros((1, res.shape[1])) + blank_symbol
+ blanked_y = tensor.concatenate([begining_blanks, res], axis=0)
+ # for y_mask
+ if y_mask is not None:
+ y_mask_extended = y_mask.T.dimshuffle(0, 1, 'x')
+ concat = tensor.concatenate([y_mask_extended,
+ y_mask_extended], axis=2)
+ res = concat.reshape((concat.shape[0],
+ concat.shape[1] * concat.shape[2])).T
+ begining_blanks = tensor.ones((1, res.shape[1]), dtype=floatX)
+ blanked_y_mask = tensor.concatenate([begining_blanks, res], axis=0)
+ else:
+ blanked_y_mask = None
+ return blanked_y, blanked_y_mask
+
+ @staticmethod
+ def class_batch_to_labeling_batch(y, y_hat, y_hat_mask=None):
+ y_hat = y_hat * y_hat_mask.dimshuffle(0, 'x', 1)
+ batch_size = y_hat.shape[2]
+ res = y_hat[:, y.astype('int32'), tensor.arange(batch_size)]
+ return res
+
+ @staticmethod
+ def recurrence_relation(y, y_mask, blank_symbol):
+ n_y = y.shape[0]
+ blanks = tensor.zeros((2, y.shape[1])) + blank_symbol
+ ybb = tensor.concatenate((y, blanks), axis=0).T
+ sec_diag = (tensor.neq(ybb[:, :-2], ybb[:, 2:]) *
+ tensor.eq(ybb[:, 1:-1], blank_symbol) *
+ y_mask.T)
+
+ # r1: LxL
+ # r2: LxL
+ # r3: LxLxB
+ r2 = tensor.eye(n_y, k=1)
+ r3 = (tensor.eye(n_y, k=2).dimshuffle(0, 1, 'x') *
+ sec_diag.dimshuffle(1, 'x', 0))
+
+ return r2, r3
+
+ @classmethod
+ def path_probabs(cls, y, y_hat, y_mask, y_hat_mask, blank_symbol):
+ pred_y = cls.class_batch_to_labeling_batch(y, y_hat, y_hat_mask)
+
+ r2, r3 = cls.recurrence_relation(y, y_mask, blank_symbol)
+
+ def step(p_curr, p_prev):
+ # instead of dot product, we * first
+ # and then sum oven one dimension.
+ # objective: T.dot((p_prev)BxL, LxLxB)
+ # solusion: Lx1xB * LxLxB --> LxLxB --> (sumover)xLxB
+ dotproduct = (p_prev + tensor.dot(p_prev, r2) +
+ (p_prev.dimshuffle(1, 'x', 0) * r3).sum(axis=0).T)
+ return p_curr.T * dotproduct * y_mask.T # B x L
+
+ probabilities, _ = theano.scan(
+ step,
+ sequences=[pred_y],
+ outputs_info=[tensor.eye(y.shape[0])[0] * tensor.ones(y.T.shape)])
+ return probabilities, probabilities.shape
+
+ @classmethod
+ def cost(cls, y, y_hat, y_mask, y_hat_mask, blank_symbol):
+ y_hat_mask_len = tensor.sum(y_hat_mask, axis=0, dtype='int32')
+ y_mask_len = tensor.sum(y_mask, axis=0, dtype='int32')
+ probabilities, sth = cls.path_probabs(y, y_hat,
+ y_mask, y_hat_mask,
+ blank_symbol)
+ batch_size = probabilities.shape[1]
+ labels_probab = (probabilities[y_hat_mask_len - 1,
+ tensor.arange(batch_size),
+ y_mask_len - 1] +
+ probabilities[y_hat_mask_len - 1,
+ tensor.arange(batch_size),
+ y_mask_len - 2])
+ avg_cost = tensor.mean(-tensor.log(labels_probab))
+ return avg_cost, sth
+
+ @staticmethod
+ def _epslog(x):
+ return tensor.cast(tensor.log(tensor.clip(x, 1E-12, 1E12)),
+ theano.config.floatX)
+
+ @staticmethod
+ def log_add(a, b):
+ max_ = tensor.maximum(a, b)
+ return (max_ + tensor.log1p(tensor.exp(a + b - 2 * max_)))
+
+ @staticmethod
+ def log_dot_matrix(x, z):
+ inf = 1E12
+ log_dot = tensor.dot(x, z)
+ zeros_to_minus_inf = (z.max(axis=0) - 1) * inf
+ return log_dot + zeros_to_minus_inf
+
+ @staticmethod
+ def log_dot_tensor(x, z):
+ inf = 1E12
+ log_dot = (x.dimshuffle(1, 'x', 0) * z).sum(axis=0).T
+ zeros_to_minus_inf = (z.max(axis=0) - 1) * inf
+ return log_dot + zeros_to_minus_inf.T
+
+ @classmethod
+ def log_path_probabs(cls, y, y_hat, y_mask, y_hat_mask, blank_symbol):
+ pred_y = cls.class_batch_to_labeling_batch(y, y_hat, y_hat_mask)
+ r2, r3 = cls.recurrence_relation(y, y_mask, blank_symbol)
+
+ def step(log_p_curr, log_p_prev):
+ p1 = log_p_prev
+ p2 = cls.log_dot_matrix(p1, r2)
+ p3 = cls.log_dot_tensor(p1, r3)
+ p123 = cls.log_add(p3, cls.log_add(p1, p2))
+
+ return (log_p_curr.T +
+ p123 +
+ cls._epslog(y_mask.T))
+
+ log_probabilities, _ = theano.scan(
+ step,
+ sequences=[cls._epslog(pred_y)],
+ outputs_info=[cls._epslog(tensor.eye(y.shape[0])[0] *
+ tensor.ones(y.T.shape))])
+ return log_probabilities
+
+ @classmethod
+ def log_cost(cls, y, y_hat, y_mask, y_hat_mask, blank_symbol):
+ y_hat_mask_len = tensor.sum(y_hat_mask, axis=0, dtype='int32')
+ y_mask_len = tensor.sum(y_mask, axis=0, dtype='int32')
+ log_probabs = cls.log_path_probabs(y, y_hat,
+ y_mask, y_hat_mask,
+ blank_symbol)
+ batch_size = log_probabs.shape[1]
+ labels_probab = cls.log_add(
+ log_probabs[y_hat_mask_len - 1,
+ tensor.arange(batch_size),
+ y_mask_len - 1],
+ log_probabs[y_hat_mask_len - 1,
+ tensor.arange(batch_size),
+ y_mask_len - 2])
+ avg_cost = tensor.mean(-labels_probab)
+ return avg_cost
+
+ @classmethod
+ def apply(cls, y, y_hat, y_mask, y_hat_mask, scale='log_scale'):
+ y_hat = y_hat.dimshuffle(0, 2, 1)
+ num_classes = y_hat.shape[1] - 1
+ blanked_y, blanked_y_mask = cls.add_blanks(
+ y=y,
+ blank_symbol=num_classes.astype(floatX),
+ y_mask=y_mask)
+ if scale == 'log_scale':
+ final_cost = cls.log_cost(blanked_y, y_hat,
+ blanked_y_mask, y_hat_mask,
+ num_classes)
+ else:
+ final_cost, sth = cls.cost(blanked_y, y_hat,
+ blanked_y_mask, y_hat_mask,
+ num_classes)
+ return final_cost
diff --git a/mohammad/ctc_test_data.pkl b/mohammad/ctc_test_data.pkl
new file mode 100644
index 0000000..2833c1b
--- /dev/null
+++ b/mohammad/ctc_test_data.pkl
Binary files differ
diff --git a/mohammad/test_ctc.py b/mohammad/test_ctc.py
new file mode 100644
index 0000000..a24d634
--- /dev/null
+++ b/mohammad/test_ctc.py
@@ -0,0 +1,135 @@
+import theano
+import numpy
+from theano import tensor
+from blocks.model import Model
+from blocks.bricks import Linear, Tanh
+from ctc_cost import CTC
+from blocks.initialization import IsotropicGaussian, Constant
+from fuel.datasets import IterableDataset
+from fuel.streams import DataStream
+from blocks.algorithms import (GradientDescent, Scale,
+ StepClipping, CompositeRule)
+from blocks.extensions.monitoring import TrainingDataMonitoring
+from blocks.main_loop import MainLoop
+from blocks.extensions import FinishAfter, Printing
+from blocks.bricks.recurrent import SimpleRecurrent
+from blocks.graph import ComputationGraph
+try:
+ import cPickle as pickle
+except:
+ import pickle
+
+floatX = theano.config.floatX
+
+
+@theano.compile.ops.as_op(itypes=[tensor.lvector],
+ otypes=[tensor.lvector])
+def print_pred(y_hat):
+ blank_symbol = 4
+ res = []
+ for i, s in enumerate(y_hat):
+ if (s != blank_symbol) and (i == 0 or s != y_hat[i - 1]):
+ res += [s]
+ return numpy.asarray(res)
+
+n_epochs = 200
+x_dim = 4
+h_dim = 9
+num_classes = 4
+
+with open("ctc_test_data.pkl", "rb") as pkl_file:
+ try:
+ data = pickle.load(pkl_file)
+ inputs = data['inputs']
+ labels = data['labels']
+ # from S x T x B x D to S x T x B
+ inputs_mask = numpy.max(data['mask_inputs'], axis=-1)
+ labels_mask = data['mask_labels']
+ except:
+ data = pickle.load(pkl_file, encoding='bytes')
+ inputs = data[b'inputs']
+ labels = data[b'labels']
+ # from S x T x B x D to S x T x B
+ inputs_mask = numpy.max(data[b'mask_inputs'], axis=-1)
+ labels_mask = data[b'mask_labels']
+
+
+
+print('Building model ...')
+# T x B x F
+x = tensor.tensor3('x', dtype=floatX)
+# T x B
+x_mask = tensor.matrix('x_mask', dtype=floatX)
+# L x B
+y = tensor.matrix('y', dtype=floatX)
+# L x B
+y_mask = tensor.matrix('y_mask', dtype=floatX)
+
+x_to_h = Linear(name='x_to_h',
+ input_dim=x_dim,
+ output_dim=h_dim)
+x_transform = x_to_h.apply(x)
+rnn = SimpleRecurrent(activation=Tanh(),
+ dim=h_dim, name="rnn")
+h = rnn.apply(x_transform)
+h_to_o = Linear(name='h_to_o',
+ input_dim=h_dim,
+ output_dim=num_classes + 1)
+h_transform = h_to_o.apply(h)
+# T x B x C+1
+y_hat = tensor.nnet.softmax(
+ h_transform.reshape((-1, num_classes + 1))
+).reshape((h.shape[0], h.shape[1], -1))
+y_hat.name = 'y_hat'
+
+y_hat_mask = x_mask
+cost = CTC().apply(y, y_hat, y_mask, y_hat_mask, 'normal_scale')
+cost.name = 'CTC'
+# Initialization
+for brick in (rnn, x_to_h, h_to_o):
+ brick.weights_init = IsotropicGaussian(0.01)
+ brick.biases_init = Constant(0)
+ brick.initialize()
+
+print('Bulding DataStream ...')
+dataset = IterableDataset({'x': inputs,
+ 'x_mask': inputs_mask,
+ 'y': labels,
+ 'y_mask': labels_mask})
+stream = DataStream(dataset)
+
+print('Bulding training process...')
+algorithm = GradientDescent(cost=cost,
+ parameters=ComputationGraph(cost).parameters,
+ step_rule=CompositeRule([StepClipping(10.0),
+ Scale(0.02)]))
+monitor_cost = TrainingDataMonitoring([cost],
+ prefix="train",
+ after_epoch=True)
+
+# sample number to monitor
+sample = 8
+
+y_hat_max_path = print_pred(tensor.argmax(y_hat[:, sample, :], axis=1))
+y_hat_max_path.name = 'Viterbi'
+monitor_output = TrainingDataMonitoring([y_hat_max_path],
+ prefix="y_hat",
+ every_n_epochs=1)
+
+length = tensor.sum(y_mask[:, sample]).astype('int32')
+tar = y[:length, sample].astype('int32')
+tar.name = '_Target_Seq'
+monitor_target = TrainingDataMonitoring([tar],
+ prefix="y",
+ every_n_epochs=1)
+
+model = Model(cost)
+main_loop = MainLoop(data_stream=stream, algorithm=algorithm,
+ extensions=[monitor_cost, monitor_output,
+ monitor_target,
+ FinishAfter(after_n_epochs=n_epochs),
+ Printing()],
+ model=model)
+
+print('Starting training ...')
+main_loop.run()