TensorFlow 1 version | View source on GitHub |
Looks up embeddings for the given ids and weights from a list of tensors.
tf.nn.embedding_lookup_sparse(
params, sp_ids, sp_weights, combiner=None, max_norm=None, name=None
)
This op assumes that there is at least one id for each row in the dense tensor represented by sp_ids (i.e. there are no rows with empty features), and that all the indices of sp_ids are in canonical row-major order.
sp_ids
and sp_weights
(if not None) are SparseTensor
s with rank of 2.
Embeddings are always aggregated along the last dimension.
It also assumes that all id values lie in the range [0, p0), where p0 is the sum of the size of params along dimension 0.
If len(params) > 1
, each element of sp_ids
is partitioned between the
elements of params
according to the "div" partition strategy, which means we
assign ids to partitions in a contiguous manner. For instance, 13 ids are
split across 5 partitions as:
[[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10], [11, 12]]
.
If the id space does not evenly divide the number of partitions, each of the
first (max_id + 1) % len(params)
partitions will be assigned one more id.
Args | |
---|---|
params
|
A single tensor representing the complete embedding tensor, or a list of tensors all of same shape except for the first dimension, representing sharded embedding tensors following "div" partition strategy. |
sp_ids
|
N x M SparseTensor of int64 ids where N is typically batch size
and M is arbitrary.
|
sp_weights
|
either a SparseTensor of float / double weights, or None to
indicate all weights should be taken to be 1. If specified, sp_weights
must have exactly the same shape and indices as sp_ids .
|
combiner
|
A string specifying the reduction op. Currently "mean", "sqrtn"
and "sum" are supported. "sum" computes the weighted sum of the embedding
results for each row. "mean" is the weighted sum divided by the total
weight. "sqrtn" is the weighted sum divided by the square root of the sum
of the squares of the weights. Defaults to mean .
|
max_norm
|
If not None , each embedding is clipped if its l2-norm is larger
than this value, before combining.
|
name
|
Optional name for the op. |
Returns | |
---|---|
A dense tensor representing the combined embeddings for the
sparse ids. For each row in the dense tensor represented by sp_ids , the op
looks up the embeddings for all ids in that row, multiplies them by the
corresponding weight, and combines these embeddings as specified.
In other words, if
and
then
For instance, if params is a 10x20 matrix, and sp_ids / sp_weights are
with
|
Raises | |
---|---|
TypeError
|
If sp_ids is not a SparseTensor , or if sp_weights is
neither None nor SparseTensor .
|
ValueError
|
If combiner is not one of {"mean", "sqrtn", "sum"}.
|