tf.contrib.lookup.IdTableWithHashBuckets

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Class `IdTableWithHashBuckets`

String to Id table wrapper that assigns out-of-vocabulary keys to buckets.

Inherits From: LookupInterface

For example, if an instance of IdTableWithHashBuckets is initialized with a string-to-id table that maps:

emerson -> 0
lake -> 1
palmer -> 2

The IdTableWithHashBuckets object will performs the following mapping:

emerson -> 0
lake -> 1
palmer -> 2
<other term> -> bucket_id, where bucket_id will be between 3 and 3 + num_oov_buckets - 1, calculated by: hash(<term>) % num_oov_buckets + vocab_size

If input_tensor is ["emerson", "lake", "palmer", "king", "crimson"], the lookup result is [0, 1, 2, 4, 7].

If table is None, only out-of-vocabulary buckets are used.

Example usage:

num_oov_buckets = 3
input_tensor = tf.constant(["emerson", "lake", "palmer", "king", "crimnson"])
table = tf.IdTableWithHashBuckets(
    tf.StaticHashTable(tf.TextFileIdTableInitializer(filename),
                       default_value),
    num_oov_buckets)
out = table.lookup(input_tensor).
table.init.run()
print(out.eval())

The hash function used for generating out-of-vocabulary buckets ID is handled by hasher_spec.

`init`

View source

__init__(
    table,
    num_oov_buckets,
    hasher_spec=tf.contrib.lookup.FastHashSpec,
    name=None,
    key_dtype=None
)

Construct a IdTableWithHashBuckets object.

Args:

table: Table that maps tf.string or tf.int64 keys to tf.int64 ids.
num_oov_buckets: Number of buckets to use for out-of-vocabulary keys.
hasher_spec: A HasherSpec to specify the hash function to use for assignation of out-of-vocabulary buckets (optional).
name: A name for the operation (optional).
key_dtype: Data type of keys passed to lookup. Defaults to table.key_dtype if table is specified, otherwise tf.string. Must be string or integer, and must be castable to table.key_dtype.

Raises:

ValueError: when table in None and num_oov_buckets is not positive.
TypeError: when hasher_spec is invalid.

Properties

`init`

DEPRECATED FUNCTION

`initializer`

`key_dtype`

The table key dtype.

`name`

The name of the table.

`resource_handle`

Returns the resource handle associated with this Resource.

`value_dtype`

The table value dtype.

Methods