张量流三重态半硬态损耗在多个时期后没有变化

2024-03-28 10:16:40 发布

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我正在编写一个基本版本的训练一个定制的人脸重新识别系统(使用mnist数据作为构建块和tensorflow定义的半硬三重丢失函数),但loss/acc在经过多个时期后完全没有变化。下面的代码


def kerasTriplet( label, pred ):
        print('-------------------------')
        print( label )
        print( pred )
        def lossFunc( y_true, y_pred ):
                return tf.contrib.losses.metric_learning.triplet_semihard_loss( label, pred, 0.6 )
                #return nonTFTripletLoss.batch_hard_triplet_loss( label, pred, 0.6 )

        return lossFunc

def gen( trg, tgt ):
        batch_sz = BATCH_SZ
        start = np.random.randint( 0, len( trg ) - BATCH_SZ )
        return trg[ start: start+batch_sz] , tgt[ start: start+batch_sz ]

(x_train, y_train), (x_test, y_test) = tf.keras.datasets.mnist.load_data()
n_train, height, width = x_train.shape
x_train = x_train.reshape(n_train, height, width, 1).astype('float32')
x_train = x_train[ :(int(len(x_train)/BATCH_SZ))*BATCH_SZ ]
x_train /= 255
num_classes = 10
y_train_orig = y_train
y_train_orig = y_train_orig[ :(int(len(x_train)/BATCH_SZ))*BATCH_SZ ]
y_train = tf.keras.utils.to_categorical(y_train, num_classes)

input_shape = (28, 28, 1)

sequence_input = tf.keras.layers.Input(shape=input_shape , dtype='float32')
batch_inp, batch_tgt = gen( x_train, y_train_orig )


x = tf.keras.layers.Conv2D( 512, (3,3), activation='relu')( batch_inp )
x = tf.keras.layers.Conv2D( 256, (3,3), activation='relu')( x )
x = tf.keras.layers.Conv2D( 128, (3,3), activation='relu')( x )

x = tf.keras.layers.Flatten()(x)
img_embedding = tf.keras.layers.Dense( 128 )(x)

## since triplet loss requires embedding to be l2 normalized
l2_embed = tf.keras.backend.l2_normalize( img_embedding, -1 )

model = tf.keras.models.Model( sequence_input , l2_embed )

model.compile( loss=kerasTriplet( batch_tgt, img_embedding ) , optimizer='adam', metrics=['acc'] )

model.fit(x_train, y_train_orig, batch_size=BATCH_SZ,  epochs=10 , verbose=1)



我预计损失和acc会发生变化,即使不会太大(因为我只跑了10个时代),但绝对是一样的。我确信这和我的代码有关。只是一根手指都插不上


Tags: returnlayerstfbatchtrainstartlabelkeras