Add support for compute_test_value inside the inner function of scan.

theano/gof/tests/test_compute_test_value.py

+import os, sys, traceback, warnings
+
 import numpy
 import unittest
 
 import theano
-import warnings
 from theano import config
 from theano import tensor as T
 from theano.tensor.basic import _allclose
@@ -164,7 +165,7 @@ class TestComputeTestValue(unittest.TestCase):
         finally:
             theano.config.compute_test_value = orig_compute_test_value
 
-    def notest_scan(self):
+    def test_scan(self):
         """
         Do not run this test as the compute_test_value mechanism is known not to work with Scan.
         TODO: fix scan to work with compute_test_value
@@ -172,15 +173,16 @@ class TestComputeTestValue(unittest.TestCase):
         orig_compute_test_value = theano.config.compute_test_value
         try:
             theano.config.compute_test_value = 'raise'
+            #theano.config.compute_test_value = 'warn'
             k = T.iscalar("k")
             A = T.vector("A")
             k.tag.test_value = 3
             A.tag.test_value = numpy.random.rand(5)
 
             def fx(prior_result, A):
-                return prior_results * A
+                return prior_result * A
             # Symbolic description of the result
-            result, updates = theano.scan(fn=lambda prior_result, A: prior_result * A,
+            result, updates = theano.scan(fn=fx,
                                           outputs_info=T.ones_like(A),
                                           non_sequences=A,
                                           n_steps=k)
@@ -192,3 +194,81 @@ class TestComputeTestValue(unittest.TestCase):
             assert hasattr(final_result.tag, 'test_value')
         finally:
             theano.config.compute_test_value = orig_compute_test_value
+
+    def test_scan_err1(self):
+        # This test should fail when building fx for the first time
+        orig_compute_test_value = theano.config.compute_test_value
+        try:
+            theano.config.compute_test_value = 'raise'
+
+            k = T.iscalar("k")
+            A = T.matrix("A")
+            k.tag.test_value = 3
+            A.tag.test_value = numpy.random.rand(5,3)
+
+            def fx(prior_result, A):
+                return T.dot(prior_result, A)
+
+            # Since we have to inspect the traceback,
+            # we cannot simply use self.assertRaises()
+            try:
+                theano.scan(
+                        fn=fx,
+                        outputs_info=T.ones_like(A),
+                        non_sequences=A,
+                        n_steps=k)
+                assert False
+            except ValueError, e:
+                # Get traceback
+                tb = sys.exc_info()[2]
+                # Get frame info 3 layers up
+                frame_info = traceback.extract_tb(tb)[-3]
+                # We should be in the "fx" function defined above
+                assert os.path.split(frame_info[0])[1] == 'test_compute_test_value.py'
+                assert frame_info[2] == 'fx'
+
+        finally:
+            theano.config.compute_test_value = orig_compute_test_value
+
+    def test_scan_err2(self):
+        # This test should not fail when building fx for the first time,
+        # but when calling the scan's perform()
+        orig_compute_test_value = theano.config.compute_test_value
+        try:
+            theano.config.compute_test_value = 'raise'
+
+            k = T.iscalar("k")
+            A = T.matrix("A")
+            k.tag.test_value = 3
+            A.tag.test_value = numpy.random.rand(5,3)
+
+            def fx(prior_result, A):
+                return T.dot(prior_result, A)
+
+            self.assertRaises(ValueError,
+                    theano.scan,
+                    fn=fx,
+                    outputs_info=T.ones_like(A.T),
+                    non_sequences=A,
+                    n_steps=k)
+
+            # Since we have to inspect the traceback,
+            # we cannot simply use self.assertRaises()
+            try:
+                theano.scan(
+                        fn=fx,
+                        outputs_info=T.ones_like(A.T),
+                        non_sequences=A,
+                        n_steps=k)
+                assert False
+            except ValueError, e:
+                # Get traceback
+                tb = sys.exc_info()[2]
+                # Get last frame info
+                frame_info = traceback.extract_tb(tb)[-1]
+                # We should be in scan_op.py, function 'perform'
+                assert os.path.split(frame_info[0])[1] == 'scan_op.py'
+                assert frame_info[2] == 'perform'
+
+        finally:
+            theano.config.compute_test_value = orig_compute_test_value

theano/scan_module/scan.py

@@ -39,6 +39,7 @@ __contact__ = "Razvan Pascanu <r.pascanu@gmail>"
 import itertools
 import logging
 import numpy
+import warnings
 
 from theano.compile import SharedVariable, function
 from theano import compile
@@ -413,10 +414,21 @@ def scan( fn
 
                 # If not we need to use copies, that will be replaced at
                 # each frame by the corresponding slice
-                _seq_val = tensor.as_tensor_variable(seq['input'])
-                nw_slice = _seq_val[0].type()
                 actual_slice = seq['input'][k-mintap]
-
+                _seq_val = tensor.as_tensor_variable(seq['input'])
+                _seq_val_slice = _seq_val[k-mintap]
+                nw_slice = _seq_val_slice.type()
+
+                # Try to transfer test_value to the new variable
+                if config.compute_test_value != 'off':
+                    try:
+                        nw_slice.tag.test_value = gof.Op._get_test_value(_seq_val_slice)
+                    except AttributeError, e:
+                        if config.compute_test_value != 'ignore':
+                            # No need to print a warning or raise an error now,
+                            # it will be done when fn will be called.
+                            info(('Cannot compute test value for the inner '
+                                'function of scan, input value missing'), e)
 
                 # Add names to slices for debugging and pretty printing ..
                 # that is if the input already has a name
@@ -451,6 +463,7 @@ def scan( fn
                 inner_slices.append( actual_slice )
                 n_seqs += 1
 
+
     # Since we've added all sequences now we need to level them up based on
     # n_steps or their different shapes
     lengths_vec = []
@@ -533,8 +546,21 @@ def scan( fn
 
             actual_arg = init_out['initial']
             arg = safe_new(init_out['initial'])
+
+            # Try to transfer test_value to the new variable
+            if config.compute_test_value != 'off':
+                try:
+                    arg.tag.test_value = gof.Op._get_test_value(actual_arg)
+                except AttributeError, e:
+                    if config.compute_test_value != 'ignore':
+                        # No need to print a warning or raise an error now,
+                        # it will be done when fn will be called.
+                        info(('Cannot compute test value for the inner '
+                            'function of scan, input value missing'), e)
+
             if getattr(init_out['initial'],'name', None) is not None:
                 arg.name = init_out['initial'].name+'[t-1]'
+
             # We need now to allocate space for storing the output and copy
             # the initial state over. We do this using the expand function
             # defined in scan utils
@@ -576,7 +602,19 @@ def scan( fn
                 # create a new slice
                 actual_nw_slice = init_out['initial'][k+mintap]
                 _init_out_var = tensor.as_tensor_variable(init_out['initial'])
-                nw_slice = _init_out_var[0].type()
+                _init_out_var_slice = _init_out_var[k+mintap]
+                nw_slice = _init_out_var_slice.type()
+
+                # Try to transfer test_value to the new variable
+                if config.compute_test_value != 'off':
+                    try:
+                        nw_slice.tag.test_value = Op._get_test_value(_init_out_var_slice)
+                    except AttributeError, e:
+                        if config.compute_test_value != 'ignore':
+                            # No need to print a warning or raise an error now,
+                            # it will be done when fn will be called.
+                            info(('Cannot compute test value for the inner '
+                                'function of scan, input value missing.'), e)
 
                 # give it a name or debugging and pretty printing
                 if getattr(init_out['initial'],'name', None) is not None: