This is similar to embedding_column, except that it produces a list of
embedding columns that share the same embedding weights.
Use this when your inputs are sparse and of the same type (e.g. watched and
impression video IDs that share the same vocabulary), and you want to convert
them to a dense representation (e.g., to feed to a DNN).
Inputs must be a list of categorical columns created by any of the
categorical_column_* function. They must all be of the same type and have
the same arguments except key. E.g. they can be
categorical_column_with_vocabulary_file with the same vocabulary_file. Some or
all columns could also be weighted_categorical_column.
Args
categorical_columns
List of categorical columns created by a
categorical_column_with_* function. These columns produce the sparse IDs
that are inputs to the embedding lookup. All columns must be of the same
type and have the same arguments except key. E.g. they can be
categorical_column_with_vocabulary_file with the same vocabulary_file.
Some or all columns could also be weighted_categorical_column.
dimension
An integer specifying dimension of the embedding, must be > 0.
combiner
A string specifying how to reduce if there are multiple entries in
a single row. Currently 'mean', 'sqrtn' and 'sum' are supported, with
'mean' the default. 'sqrtn' often achieves good accuracy, in particular
with bag-of-words columns. Each of this can be thought as example level
normalizations on the column. For more information, see
tf.embedding_lookup_sparse.
initializer
A variable initializer function to be used in embedding
variable initialization. If not specified, defaults to
truncated_normal_initializer with mean 0.0 and standard deviation
1/sqrt(dimension).
shared_embedding_collection_name
Optional collective name of these columns.
If not given, a reasonable name will be chosen based on the names of
categorical_columns.
ckpt_to_load_from
String representing checkpoint name/pattern from which to
restore column weights. Required if tensor_name_in_ckpt is not None.
tensor_name_in_ckpt
Name of the Tensor in ckpt_to_load_from from which
to restore the column weights. Required if ckpt_to_load_from is not
None.
max_norm
If not None, each embedding is clipped if its l2-norm is larger
than this value, before combining.
trainable
Whether or not the embedding is trainable. Default is True.
use_safe_embedding_lookup
If true, uses safe_embedding_lookup_sparse
instead of embedding_lookup_sparse. safe_embedding_lookup_sparse ensures
there are no empty rows and all weights and ids are positive at the
expense of extra compute cost. This only applies to rank 2 (NxM) shaped
input tensors. Defaults to true, consider turning off if the above checks
are not needed. Note that having empty rows will not trigger any error
though the output result might be 0 or omitted.
Returns
A list of dense columns that converts from sparse input. The order of
results follows the ordering of categorical_columns.
Raises
ValueError
if dimension not > 0.
ValueError
if any of the given categorical_columns is of different type
or has different arguments than the others.
ValueError
if exactly one of ckpt_to_load_from and tensor_name_in_ckpt
is specified.