EmbeddingBagPackedSum¶

Versioned name : EmbeddingBagPackedSum-3

Category : Sparse

Short description : Computes sums of “bags” of embeddings, without instantiating the intermediate embeddings.

Detailed description : This is the first case of the PyTorch EmbeddingBag, it has indices in the tensor of format [batch, indices_per_bag]. If 3rd input is not provided, this operation is equivalent to Gather followed by ReduceSum(axis=0). However, EmbeddingBagPackedSum is much more time and memory efficient than using a chain of these operations.

Attributes : EmbeddingBagPackedSum operation has no attributes.

Inputs :

1 : emb_table tensor containing the embedding lookup table of the module of shape [num_emb, emb_dim1, emb_dim2, ...] and of type T. Required.
2 : indices tensor of shape [batch, indices_per_bag] and of type T_IND. Required.
3 : per_sample_weights tensor of the same shape as indices and of type T. Each value in this tensor are multiplied with each value pooled from embedding table for each index. Optional, default is tensor of ones.

Outputs :

1 : tensor of shape [batch, emb_dim1, emb_dim2, ...] and of type T containing embeddings for each bag.

Types

T : any numeric type.
T_IND : int32 or int64.

Example

<layer ... type="EmbeddingBagPackedSum" ... >
    <input>
        <port id="0">     <!-- emb_table value is: [[-0.2, -0.6], [-0.1, -0.4], [-1.9, -1.8], [-1.,  1.5], [ 0.8, -0.7]] -->
            <dim>5</dim>
            <dim>2</dim>
        </port>
        <port id="1">     <!-- indices value is: [[0, 2], [1, 2], [3, 4]] -->
            <dim>3</dim>
            <dim>2</dim>
        </port>
        <port id="2"/>    <!-- per_sample_weigths value is: [[0.5, 0.5], [0.5, 0.5], [0.5, 0.5]] -->
            <dim>3</dim>
            <dim>2</dim>
        </port>
    </input>
    <output>
        <port id="4">     <!-- output value is: [[-1.05, -1.2], [-1., -1.1], [-0.1, 0.4]] -->
            <dim>3</dim>
            <dim>2</dim>
        </port>
    </output>
</layer>

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