don't raise an AssertionError when it is a case that is not implemented.

theano/tensor/basic.py

@@ -374,9 +374,10 @@ def get_constant_value(v):
             if isinstance(v.owner.inputs[0], TensorConstant):
                 return v.owner.inputs[0].data.__getitem__(tuple(v.owner.op.idx_list))
 
-            # The index list 'idx_list' should have length one
-            # since joining scalar variables results in a 1D vector.
-            assert len(v.owner.op.idx_list) == 1
+            # The index list 'idx_list' should have length the same shape as the
+            # input.
+            # TODO: implement the case where we take a scalar in a matrix
+            assert len(v.owner.op.idx_list) == v.owner.inputs[0].ndim
 
             #Needed to make better graph in this test.
             #theano/tensor/tests/test_sharedvar.py:test_shared_options.test_specify_shape_partial
@@ -385,7 +386,8 @@ def get_constant_value(v):
                 # Ensure the Join is joining only scalar variables (so that
                 # the constant value can be found at the same index as the one
                 # used in the sub-tensor).
-                all(var.ndim==0 for var in v.owner.inputs[0].owner.inputs)):
+                all(var.ndim==0 for var in v.owner.inputs[0].owner.inputs) and
+                len(v.owner.op.idx_list) == 1):
 
                 # Note the '+ 1' is because the first argument to Join is the
                 # axis.
@@ -398,7 +400,8 @@ def get_constant_value(v):
                            theano.tensor.opt.MakeVector) and
                 # MakeVector normally accept only scalar as input.
                 # We put this check in case there is change in the future
-                all(var.ndim==0 for var in v.owner.inputs[0].owner.inputs)):
+                all(var.ndim==0 for var in v.owner.inputs[0].owner.inputs) and
+                len(v.owner.op.idx_list) == 1):
 
                 ret = v.owner.inputs[0].owner.inputs[v.owner.op.idx_list[0]]
                 ret = get_constant_value(ret)