对input list按元素求和, 输出的shape和输入的shape相同.
示例:
input_shape = (2, 3, 4)
x1 = tf.random.normal(input_shape)
x2 = tf.random.normal(input_shape)
y = tf.keras.layers.Add()([x1, x2])
print(y.shape)
input1 = tf.keras.layers.Input(shape=(16,))
x1 = tf.keras.layers.Dense(8, activation='relu')(input1)
input2 = tf.keras.layers.Input(shape=(32,))
x2 = tf.keras.layers.Dense(8, activation='relu')(input2)
# equivalent to `added = tf.keras.layers.add([x1, x2])`
added = tf.keras.layers.Add()([x1, x2])
out = tf.keras.layers.Dense(4)(added)
model = tf.keras.models.Model(inputs=[input1, input2], outputs=out)