# tf.contrib.lookup.MutableHashTable

## Class MutableHashTable

Inherits From: LookupInterface

A generic mutable hash table implementation.

Data can be inserted by calling the insert method. It does not support initialization via the init method.

Example usage:

table = tf.contrib.lookup.MutableHashTable(key_dtype=tf.string,
value_dtype=tf.int64,
default_value=-1)
sess.run(table.insert(keys, values))
out = table.lookup(query_keys)
print(out.eval())


## Properties

### init

The table initialization op.

### key_dtype

The table key dtype.

### name

The name of the table.

### value_dtype

The table value dtype.

## Methods

### __init__

__init__(
key_dtype,
value_dtype,
default_value,
shared_name=None,
name='MutableHashTable',
checkpoint=True
)


Creates an empty MutableHashTable object.

Creates a table, the type of its keys and values are specified by key_dtype and value_dtype, respectively.

#### 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.
• shared_name: If non-empty, this table will be shared under the given name across multiple sessions.
• 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.

#### Returns:

A MutableHashTable object.

#### Raises:

• ValueError: If checkpoint is True and no name was specified.

### export

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

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

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. Can be a tensor of any shape. Must match the table's key_dtype.
• 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.

### size

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.