`AdditiveAttention`

class```
keras.layers.AdditiveAttention(use_scale=True, dropout=0.0, **kwargs)
```

Additive attention layer, a.k.a. Bahdanau-style attention.

Inputs are a list with 2 or 3 elements:
1. A `query`

tensor of shape `(batch_size, Tq, dim)`

.
2. A `value`

tensor of shape `(batch_size, Tv, dim)`

.
3. A optional `key`

tensor of shape `(batch_size, Tv, dim)`

. If none
supplied, `value`

will be used as `key`

.

The calculation follows the steps:
1. Calculate attention scores using `query`

and `key`

with shape
`(batch_size, Tq, Tv)`

as a non-linear sum
`scores = reduce_sum(tanh(query + key), axis=-1)`

.
2. Use scores to calculate a softmax distribution with shape
`(batch_size, Tq, Tv)`

.
3. Use the softmax distribution to create a linear combination of `value`

with shape `(batch_size, Tq, dim)`

.

**Arguments**

**use_scale**: If`True`

, will create a scalar variable to scale the attention scores.**dropout**: Float between 0 and 1. Fraction of the units to drop for the attention scores. Defaults to`0.0`

.

**Call arguments**

**inputs**: List of the following tensors:`query`

: Query tensor of shape`(batch_size, Tq, dim)`

.`value`

: Value tensor of shape`(batch_size, Tv, dim)`

.`key`

: Optional key tensor of shape`(batch_size, Tv, dim)`

. If not given, will use`value`

for both`key`

and`value`

, which is the most common case.

**mask**: List of the following tensors:`query_mask`

: A boolean mask tensor of shape`(batch_size, Tq)`

. If given, the output will be zero at the positions where`mask==False`

.`value_mask`

: A boolean mask tensor of shape`(batch_size, Tv)`

. If given, will apply the mask such that values at positions where`mask==False`

do not contribute to the result.

**return_attention_scores**: bool, it`True`

, returns the attention scores (after masking and softmax) as an additional output argument.**training**: Python boolean indicating whether the layer should behave in training mode (adding dropout) or in inference mode (no dropout).**use_causal_mask**: Boolean. Set to`True`

for decoder self-attention. Adds a mask such that position`i`

cannot attend to positions`j > i`

. This prevents the flow of information from the future towards the past. Defaults to`False`

.

Output:
Attention outputs of shape `(batch_size, Tq, dim)`

.
(Optional) Attention scores after masking and softmax with shape
`(batch_size, Tq, Tv)`

.