A generic mutable hash table implementation.
Inherits From: TrackableResource
tf.lookup.experimental.MutableHashTable(
key_dtype,
value_dtype,
default_value,
name='MutableHashTable',
checkpoint=True,
experimental_is_anonymous=False
)
Data can be inserted by calling the insert
method and removed by calling the
remove
method. It does not support initialization via the init method.
MutableHashTable
requires additional memory during checkpointing and restore
operations to create temporary key and value tensors.
Example usage:
table = tf.lookup.experimental.MutableHashTable(key_dtype=tf.string,
value_dtype=tf.int64,
default_value=-1)
keys_tensor = tf.constant(['a', 'b', 'c'])
vals_tensor = tf.constant([7, 8, 9], dtype=tf.int64)
input_tensor = tf.constant(['a', 'f'])
table.insert(keys_tensor, vals_tensor)
table.lookup(input_tensor).numpy()
array([ 7, -1])
table.remove(tf.constant(['c']))
table.lookup(keys_tensor).numpy()
array([ 7, 8, -1])
sorted(table.export()[0].numpy())
[b'a', b'b']
sorted(table.export()[1].numpy())
[7, 8]
Args |
key_dtype
|
the type of the key tensors.
|
value_dtype
|
the type of the value tensors.
|
default_value
|
The value to use if a key is missing in the table.
|
name
|
A name for the operation (optional).
|
checkpoint
|
if True, the contents of the table are saved to and restored
from checkpoints. If shared_name is empty for a checkpointed table, it
is shared using the table node name.
|
experimental_is_anonymous
|
Whether to use anonymous mode for the
table (default is False). In anonymous mode, the table
resource can only be accessed via a resource handle. It can't
be looked up by a name. When all resource handles pointing to
that resource are gone, the resource will be deleted
automatically.
|
Raises |
ValueError
|
If checkpoint is True and no name was specified.
|
Attributes |
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.
|
insert
View source
insert(
keys, values, name=None
)
Associates keys
with values
.
Args |
keys
|
Keys to insert. Can be a tensor of any shape. Must match the table's
key type.
|
values
|
Values to be associated with keys. Must be a tensor of the same
shape as keys and match the table's value type.
|
name
|
A name for the operation (optional).
|
Returns |
The created Operation.
|
Raises |
TypeError
|
when keys or values doesn't match the table data
types.
|
lookup
View source
lookup(
keys, dynamic_default_values=None, 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. Can be a tensor of any shape. Must match the
table's key_dtype.
|
dynamic_default_values
|
The values to use if a key is missing in the
table. If None (by default), the table.default_value will be used.
Shape of dynamic_default_values must be same with
table.default_value or the lookup result tensor.
In the latter case, each key will have a different default value.
For example:
keys = [0, 1, 3]
dynamic_default_values = [[1, 3, 4], [2, 3, 9], [8, 3, 0]]
# The key '0' will use [1, 3, 4] as default value.
# The key '1' will use [2, 3, 9] as default value.
# The key '3' will use [8, 3, 0] as default value.
|
name
|
A name for the operation (optional).
|
Returns |
A tensor containing the values in the same shape as keys using the
table's value type.
|
Raises |
TypeError
|
when keys do not match the table data types.
|
remove
View source
remove(
keys, name=None
)
Removes keys
and its associated values from the table.
If a key is not present in the table, it is silently ignored.
Args |
keys
|
Keys to remove. Can be a tensor of any shape. Must match the table's
key type.
|
name
|
A name for the operation (optional).
|
Returns |
The created Operation.
|
Raises |
TypeError
|
when keys do not 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.