tf.lookup.StaticHashTable

A generic hash table that is immutable once initialized.

Inherits From: TrackableResource

tf.lookup.StaticHashTable(
    initializer, default_value, name=None
)

Example usage:

keys_tensor = tf.constant(['a', 'b', 'c'])
vals_tensor = tf.constant([7, 8, 9])
input_tensor = tf.constant(['a', 'f'])
table = tf.lookup.StaticHashTable(
    tf.lookup.KeyValueTensorInitializer(keys_tensor, vals_tensor),
    default_value=-1)
table.lookup(input_tensor).numpy()
array([ 7, -1], dtype=int32)

Or for more pythonic code:

table[input_tensor].numpy()
array([ 7, -1], dtype=int32)

The result of a lookup operation has the same shape as the argument:

input_tensor = tf.constant([['a', 'b'], ['c', 'd']])
table[input_tensor].numpy()
array([[ 7,  8],
       [ 9, -1]], dtype=int32)

Args
initializer	The table initializer to use. See HashTable kernel for supported key and value types.
default_value	The value to use if a key is missing in the table.
name	A name for the operation (optional).

Attributes
default_value	The default value of the table.
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

export

View source

export(
    name=None
)

Returns tensors of all keys and values in the table.

Args
name	A name for the operation (optional).

Returns
A pair of tensors with the first tensor containing all keys and the second tensors containing all values in the table.

lookup

View source

lookup(
    keys, name=None
)

Looks up keys in a table, outputs the corresponding values.

The default_value is used for keys not present in the table.

Args
keys	Keys to look up. May be either a SparseTensor or dense Tensor.
name	A name for the operation (optional).

Returns
A SparseTensor if keys are sparse, a RaggedTensor if keys are ragged, otherwise a dense Tensor.

Raises
TypeError	when keys or default_value doesn't match the table data types.

size

View source

size(
    name=None
)

Compute the number of elements in this table.

Args
name	A name for the operation (optional).

Returns
A scalar tensor containing the number of elements in this table.

__getitem__

View source

__getitem__(
    keys
)

Looks up keys in a table, outputs the corresponding values.