Merge pull request #1566 from lamblin/fix_scan_linesearch

theano/scan_module/scan_opt.py

@@ -118,25 +118,26 @@ def remove_constants_and_unused_inputs_scan(node):
     # Add outputs stuff
     nw_inner += out_stuff_inner
     nw_outer += out_stuff_outer
+
     # Look through non sequences
+    nw_inner_nonseq = []
+    nw_outer_nonseq = []
     for idx, (nw_in, nw_out) in enumerate(zip(non_seqs, outer_non_seqs)):
         if isinstance(nw_out, tensor.Constant):
             givens[nw_in] = nw_out.clone()
         elif nw_in in all_ins:
-            identical_non_seqs = [x for x in nw_outer
-                                  if scan_utils.equal_computations(
-                                      [x], [nw_out])]
-            if identical_non_seqs:
-                identical_idx = outer_non_seqs.index(identical_non_seqs[0])
-                # If we have identical non sequences, the previous one
-                # must be in nw_inner or be a constant.
-                assert (non_seqs[identical_idx] in nw_inner or
-                        isinstance(identical_non_seqs[0], tensor.Constant))
-                index = outer_non_seqs.index(identical_non_seqs[0])
-                givens[nw_in] = non_seqs[index]
+            # Indices of elements of nw_outer_nonseq that are equivalent
+            # to nw_out.
+            identical_nonseq_idx = [
+                i for (i, x) in enumerate(nw_outer_nonseq)
+                if scan_utils.equal_computations([x], [nw_out])]
+            if identical_nonseq_idx:
+                givens[nw_in] = nw_inner_nonseq[identical_nonseq_idx[0]]
             else:
-                nw_inner += [nw_in]
-                nw_outer += [nw_out]
+                nw_inner_nonseq += [nw_in]
+                nw_outer_nonseq += [nw_out]
+    nw_inner.extend(nw_inner_nonseq)
+    nw_outer.extend(nw_outer_nonseq)
 
     if len(nw_inner) != len(op_ins):
         op_outs = scan_utils.clone(op_outs, replace=givens)