Merge pull request #22 from tensorflow/embedding-lookup-fix

Embedding lookup fix

tensorflow-ops/src/TensorFlow/EmbeddingOps.hs

@@ -23,9 +23,8 @@ module TensorFlow.EmbeddingOps where
 
 import Control.Monad (zipWithM)
 import Data.Int (Int32, Int64)
-import Data.List (genericLength)
 import TensorFlow.Build (Build, colocateWith, render)
-import TensorFlow.Ops ()  -- Num instance for Tensor
+import TensorFlow.Ops (scalar, shape, vector)  -- Also Num instance for Tensor
 import TensorFlow.Tensor (Tensor, Value)
 import TensorFlow.Types (OneOf, TensorType)
 import qualified TensorFlow.GenOps.Core as CoreOps
@@ -56,21 +55,34 @@ embeddingLookup :: forall a b v .
                 -> Tensor Value b
                 -- ^ A `Tensor` with type `int32` or `int64`
                 -- containing the ids to be looked up in `params`.
-                -- The ids are required to be flat on entry and have
-                -- fewer than 2^31 entries.
+                -- The ids are required to have fewer than 2^31
+                -- entries.
                 -> Build (Tensor Value a)
                 -- ^ A dense tensor with shape `shape(ids) + shape(params)[1:]`.
-embeddingLookup params ids =
-    CoreOps.dynamicStitch pindices <$> partitionedResult
-  where np = genericLength params
-        pAssignments = CoreOps.cast (ids `CoreOps.mod` np)
-        newIds = ids `CoreOps.div` np
-        originalIndices = CoreOps.range 0 (CoreOps.size ids) 1
+embeddingLookup [p0] ids = colocateWith p0 (render $ CoreOps.gather p0 ids)
+embeddingLookup params@(p0 : _) ids = do
+    -- Do np separate lookups, finding embeddings for plist[p] in params[p]
+    partitionedResult <- zipWithM
+                        (\p g -> colocateWith p $ render $ CoreOps.gather p g)
+                        params gatherIds
+    let unshapedResult = CoreOps.dynamicStitch pindices partitionedResult
+    -- Shape restoration is not as optimal as it would be with client
+    -- side shape tracking.
+    paramShape <- colocateWith p0 (render (shape p0))
+    let finalShape = CoreOps.concat 0 [shape ids, tailShape]
+        tailShape = CoreOps.slice paramShape (singleton 1) (singleton (-1))
+    render $ CoreOps.reshape unshapedResult finalShape
+  where
+    -- Avoids genericLength here which would be evaluated by TF.
+    np = fromIntegral (length params)
+    flatIds = CoreOps.reshape ids (singleton (-1))
+    pAssignments = CoreOps.cast (flatIds `CoreOps.mod` np)
+    newIds = flatIds `CoreOps.div` np
+    originalIndices = CoreOps.range 0 (CoreOps.size flatIds) 1
     -- Partition list of ids based on assignments into np separate lists
     gatherIds = CoreOps.dynamicPartition np newIds pAssignments
     -- Similarly, partition the original indices.
     pindices = CoreOps.dynamicPartition np originalIndices pAssignments
-        -- Do np separate lookups, finding embeddings for plist[p] in params[p]
-        partitionedResult = zipWithM
-                            (\p g -> colocateWith p $ render $ CoreOps.gather p g)
-                            params gatherIds
+    singleton i = vector [i :: Int32]
+
+embeddingLookup [] _ = error "embeddingLookup requires params to be non empty"

tensorflow-ops/tests/EmbeddingOpsTest.hs

@@ -24,6 +24,7 @@ import Google.Test (googleTest)
 import TensorFlow.EmbeddingOps (embeddingLookup)
 import Test.Framework.Providers.QuickCheck2 (testProperty)
 import Test.HUnit ((@=?))
+import Test.Framework.Providers.HUnit (testCase)
 import Test.QuickCheck (Arbitrary(..), Property, choose, vectorOf)
 import Test.QuickCheck.Monadic (monadicIO, run)
 
@@ -34,6 +35,56 @@ import qualified TensorFlow.Session as TF
 import qualified TensorFlow.Tensor as TF
 import qualified TensorFlow.Types as TF
 
+
+buildAndRun = TF.runSession . TF.buildAnd TF.run
+
+-- | Tries to perform a simple embedding lookup, with two partitions.
+testEmbeddingLookupHasRightShapeWithPartition = testCase "testEmbeddingLookupHasRightShapeWithPartition" $ do
+    let shape       = TF.Shape [1, 3] -- Consider a 3-dim embedding of two items.
+    let embedding1  = [ 1, 1, 1 ] :: [Int32]
+    let embedding2  = [ 0, 0, 0 ] :: [Int32]
+
+    let embedding = [ TF.constant shape embedding1
+                    , TF.constant shape embedding2
+                    ]
+
+    let idValues  = [0, 1] :: [Int32]
+    let ids       = TF.constant (TF.Shape [1, 2]) idValues
+    let op        = embeddingLookup embedding ids
+
+    (values, shape) <- buildAndRun $ do
+        vs <- op
+        return (vs, TF.shape vs)
+
+    -- This is the shape that is returned in the equiv. Python.
+    shape  @=? V.fromList [ 1, 2, 3 ]
+
+    -- "[0, 1]" should pull out the resulting vector.
+    values @=? V.fromList [ 1, 1, 1, 0, 0, 0 ]
+
+
+-- | Tries to perform a simple embedding lookup, with only a single partition.
+testEmbeddingLookupHasRightShape = testCase "testEmbeddingLookupHasRightShape" $ do
+    let shape         = TF.Shape [2, 3] -- Consider a 3-dim embedding of two items.
+    let embeddingInit = [ 1, 1, 1
+                        , 0, 0, 0 ] :: [Int32]
+
+    let embedding = TF.constant shape embeddingInit
+    let idValues  = [0, 1] :: [Int32]
+    let ids       = TF.constant (TF.Shape [1, 2]) idValues
+    let op        = embeddingLookup [embedding] ids
+
+    (values, shape) <- buildAndRun $ do
+        vs <- op
+        return (vs, TF.shape vs)
+
+    -- This is the shape that is returned in the equiv. Python.
+    shape  @=? V.fromList [ 1, 2, 3 ]
+
+    -- "[0, 1]" should pull out the resulting vector.
+    values @=? V.fromList [ 1, 1, 1, 0, 0, 0 ]
+
+
 -- Verifies that direct gather is the same as dynamic split into
 -- partitions, followed by embedding lookup.
 testEmbeddingLookupUndoesSplit :: forall a. (TF.TensorType a, Show a, Eq a)
@@ -85,4 +136,6 @@ main :: IO ()
 main = googleTest
        [ testProperty "EmbeddingLookupUndoesSplit"
          (testEmbeddingLookupUndoesSplit :: LookupExample Double -> Property)
+       , testEmbeddingLookupHasRightShape
+       , testEmbeddingLookupHasRightShapeWithPartition
        ]