Merge pull request #59 from goodfeli/get_test_value

theano/gof/op.py

@@ -344,7 +344,7 @@ class PureOp(object):
             # ensure that the test value is correct
             return v.type.filter(v.tag.test_value)
 
-        raise AttributeError('%s has not test value' % v)
+        raise AttributeError('%s has no test value' % v)
 
     def __call__(self, *inputs, **kwargs):
         """Optional: Return some or all output[s] of `make_node`.
@@ -545,3 +545,21 @@ class Op(utils.object2, PureOp, CLinkerOp):
         rval.perform = p
         rval.lazy = False
         return rval
+
+
+def get_test_value(v):
+    """
+    Extract test value from variable v. Raises AttributeError if there is none.
+
+    For an ndarray, the value is the ndarray itself
+    For a Constant, the test value is v.value.
+    For a Shared variable, it is the internal value.
+    For another Variable, it is the content of v.tag.test_value."""
+
+    try:
+        return PureOp._get_test_value(v)
+    except AttributeError:
+        if hasattr(v,'__array__'):
+            return v
+        raise
+

theano/gof/tests/test_op.py

@@ -5,11 +5,17 @@ import numpy
 
 import theano
 
-from theano.gof.op import *
+import theano.gof.op as op
 from theano.gof.type import Type, Generic
 from theano.gof.graph import Apply, Variable
-
+import theano.tensor as T
 from theano import scalar
+from theano import shared
+
+config = theano.config
+Op = op.Op
+utils = op.utils
+
 
 def as_variable(x):
     assert isinstance(x, Variable)
@@ -182,5 +188,33 @@ class TestMakeThunk(unittest.TestCase):
         assert compute_map[o][0]
         assert storage_map[o][0] == 4
 
+def test_test_value_ndarray():
+    x = numpy.zeros((5,5))
+    v = op.get_test_value(x)
+    assert v is x
+
+def test_test_value_constant():
+    x = T.as_tensor_variable(numpy.zeros((5,5)))
+    v = op.get_test_value(x)
+
+    assert numpy.all(v == numpy.zeros((5,5)))
+
+def test_test_value_shared():
+    x = shared(numpy.zeros((5,5)))
+    v = op.get_test_value(x)
+
+    assert numpy.all(v == numpy.zeros((5,5)))
+
+def test_test_value_op():
+    try:
+        prev_value = config.compute_test_value
+        config.compute_test_value = 'raise'
+        x = T.log(numpy.ones((5,5)))
+        v = op.get_test_value(x)
+
+        assert numpy.allclose(v, numpy.zeros((5,5)))
+    finally:
+        config.compute_test_value = prev_value
+
 if __name__ == '__main__':
     unittest.main()