added non-inplace version of SetSubtensor

theano/tensor/basic.py

@@ -1140,7 +1140,7 @@ class Subtensor(Op):
             helper(idx)
         return ret
 
-    def __init__(self, idx_list):
+    @staticmethod
     def convert(entry, slice_ok=True):
         scal_types = [scal.int64, scal.int32, scal.int16, scal.int8]
         tensor_types = [bscalar, iscalar, lscalar]
@@ -1156,14 +1156,16 @@ class Subtensor(Op):
             a = entry.start
             b = entry.stop
             c = entry.step
-                return slice(convert(a, False) if a is not None else None,
-                             convert(b, False) if b is not None else None,
-                             convert(c, False) if c is not None else None)
+            return slice(Subtensor.convert(a, False) if a is not None else None,
+                         Subtensor.convert(b, False) if b is not None else None,
+                         Subtensor.convert(c, False) if c is not None else None)
         elif isinstance(entry, int):
             return entry
         else:
             raise TypeError(Subtensor.e_indextype, entry)
-        self.idx_list = map(convert, idx_list)
+
+    def __init__(self, idx_list):
+        self.idx_list = map(self.convert, idx_list)
 
     def make_node(self, x, *inputs):
         x = as_tensor(x)
@@ -1269,10 +1271,42 @@ pprint.assign(lambda pstate, r: r.owner and isinstance(r.owner.op, Subtensor), S
 
 
 
-class SetSubtensor(Subtensor):
-    """WRITEME"""
-    view_map = {}
-    destroy_map = {0: [0]}
+class SetSubtensor(Op):
+    """Set just some elements of a larger Tensor.
+
+    This is like numpy's 
+
+        z[i,j,k] = <something> 
+    
+    """
+
+    def __init__(self, idx_list, inplace=False):
+        self.idx_list = map(Subtensor.convert, idx_list)
+        self.inplace = inplace
+        if inplace:
+            self.destroy_map = {0: [0]}
+
+    def __eq__(self, other):
+        return type(self) == type(other) \
+                and self.idx_list == other.idx_list \
+                and self.inplace == other.inplace
+
+    def __hash__(self):
+        idx_list = tuple((entry.start, entry.stop, entry.step)
+                         if isinstance(entry, slice)
+                         else entry
+                         for entry in self.idx_list)
+        return hash(type(self)) ^ hash(idx_list) ^ hash(self.inplace)
+
+    def __str__(self):
+        indices = []
+        for entry in self.idx_list:
+            if isinstance(entry, slice):
+                indices.append(":".join("" if x is None else str(x) for x in [entry.start, entry.stop, entry.step]))
+            else:
+                indices.append(str(entry))
+        return "%s%s{%s}" % ('Inplace' if self.inplace else '',
+                self.__class__.__name__, ", ".join(indices))
 
     def make_node(self, x, y, *inputs):
         x, y = map(as_tensor, [x, y])
@@ -1318,6 +1352,8 @@ class SetSubtensor(Subtensor):
         cdata = tuple(map(convert, self.idx_list))
         if len(cdata) == 1:
             cdata = cdata[0]
+        if not self.inplace:
+            x = x.copy()
         x.__setitem__(cdata, y)
         out[0] = x
 

theano/tensor/opt.py

@@ -5,7 +5,7 @@
 
 
 from .. import gof
-from ..gof import opt, InconsistencyError
+from ..gof import opt, InconsistencyError, TopoOptimizer
 from elemwise import Elemwise, DimShuffle
 from .. import scalar
 import basic as T
@@ -273,6 +273,17 @@ def local_subtensor_make_vector(node):
 
 register_canonicalize(local_subtensor_make_vector)
 
+#after priority 50 Destructive inplace operations
+#gemm is the first one now, at priority 70
+
+@gof.local_optimizer([None])
+def local_inplace_setsubtensor(node):
+    if isinstance(node.op, T.SetSubtensor) and not node.op.inplace:
+        new_op = T.SetSubtensor(node.op.idx_list, inplace=True)
+        new_node = new_op(*node.inputs)
+        return new_node.outputs
+    return False
+compile.optdb.register('inplace_setsubtensor', TopoOptimizer(local_inplace_setsubtensor), 60, 'fast_run', 'inplace') #DEBUG
 
 ##################
 # Middleman cuts #