用tensorflow写一个包含多头注意力机制的模型代码

好的，以下是使用TensorFlow实现多头注意力机制的模型代码：

import tensorflow as tf

class MultiHeadAttention(tf.keras.layers.Layer):
    def __init__(self, num_heads, d_model):
        super(MultiHeadAttention, self).__init__()
        self.num_heads = num_heads
        self.d_model = d_model
        
        assert d_model % self.num_heads == 0
        
        self.depth = d_model // self.num_heads
        
        self.wq = tf.keras.layers.Dense(d_model)
        self.wk = tf.keras.layers.Dense(d_model)
        self.wv = tf.keras.layers.Dense(d_model)
        
        self.dense = tf.keras.layers.Dense(d_model)

    def split_heads(self, x, batch_size):
        x = tf.reshape(x, (batch_size, -1, self.num_heads, self.depth))
        return tf.transpose(x, perm=[0, 2, 1, 3])

    def call(self, v, k, q, mask):
        batch_size = tf.shape(q)[0]
        
        q = self.wq(q)  
        k = self.wk(k)  
        v = self.wv(v)  
        
        q = self.split_heads(q, batch_size)  
        k = self.split_heads(k, batch_size)  
        v = self.split_heads(v, batch_size)  
        
        scaled_attention, attention_weights = scaled_dot_product_attention(q, k, v, mask)
        
        scaled_attention = tf.transpose(scaled_attention, perm=[0, 2, 1, 3])  
        concat_attention = tf.reshape(scaled_attention, (batch_size, -1, self.d_model))  
        
        output = self.dense(concat_attention)
        
        return output, attention_weights

def scaled_dot_product_attention(q, k, v, mask):
    matmul_qk = tf.matmul(q, k, transpose_b=True)
    
    dk = tf.cast(tf.shape(k)[-1], tf.float32)
    scaled_attention_logits = matmul_qk / tf.math.sqrt(dk)

    if mask is not None:
        scaled_attention_logits += (mask * -1e9)  

    attention_weights = tf.nn.softmax(scaled_attention_logits, axis=-1)
    output = tf.matmul(attention_weights, v)  

    return output, attention_weights

希望可以帮到你，如有疑问欢迎随时提出。