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我是 tensorflow 和深度学习的新手。

我创建了一个自定义损失函数，但似乎在自定义损失函数中，未启用急切执行。下面是我的自定义损失函数（它不起作用）：

def custom_error_finder(y_actual,y_pred):
    print(tf.executing_eagerly())
    count = 0
    qw = tf.py_function((y_actual).numpy())
    ya = ((y_actual[0].numpy()).decode())
    yp = ((y_pred[0].numpy()).decode())
    for i,j in ya,yp:
        if i!=j:
            count = count+1
    mse = pow(count,2)/len(ya)
    return mse

让我难过的是，在这个函数之外，每当我运行时print(tf.executing_eagerly())，它都会返回 true，但在函数内部，它会返回 false。

我已经尝试了所有我能找到的修复：

- 传入 model.compile run_eagerly = True() 函数

-model.run_eagerly() = True在编译函数之后添加

-tf.compat.v1.enable_eager_execution()在损失函数中运行以至少强制急切执行一次。

以上修复均无效。

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1 回答 1

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我能够重现如下问题。您可以从这里下载我在程序中使用的数据集。我print("tf.executing_eagerly() Results")在程序中添加了语句来跟踪更改。

代码 -

%tensorflow_version 2.x
import tensorflow as tf
print(tf.__version__)
import numpy as np
from numpy import loadtxt
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense
from tensorflow.keras import backend as K

print("tf.executing_eagerly() Results")
print("Before loading dataset :",tf.executing_eagerly())

# load pima indians dataset
dataset = np.loadtxt("/content/pima-indians-diabetes.csv", delimiter=",")

# split into input (X) and output (Y) variables
X = dataset[:,0:8]
Y = dataset[:,8]

# define model
model = Sequential()
model.add(Dense(12, input_dim=8, activation='relu'))
model.add(Dense(8, activation='relu'))
model.add(Dense(1, activation='sigmoid'))

print("After building model :",tf.executing_eagerly())

def weighted_binary_crossentropy(y_true, y_pred):
  print("In loss function :",tf.executing_eagerly())
  return K.mean(K.binary_crossentropy(y_pred, y_true))

# compile model
model.compile(loss=weighted_binary_crossentropy, optimizer='adam', metrics=['accuracy'])

print("After compiling model :",tf.executing_eagerly())

# Fit the model
model.fit(X, Y, epochs=1, batch_size=150, verbose=0)

# evaluate the model
scores = model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (model.metrics_names[1], scores[1]*100))

输出 -

2.2.0
tf.executing_eagerly() Results
Before loading dataset : True
After building model : True
After compiling model : True
In loss function : False
In loss function : False
In loss function : False
accuracy: 34.90%

解决方案 -根据文档。它提到，

run_eagerly - 指示模型是否应该急切运行的可设置属性。急切地运行意味着您的模型将像 Python 代码一样逐步运行。您的模型可能会运行得更慢，但通过单步调用各个层调用，您应该可以更轻松地对其进行调试。默认情况下，我们将尝试将您的模型编译为静态图以提供最佳执行性能。

如果我们修改model.compilewithrun_eagerly = True参数，我们可以解决这个问题。下图是修改后的model.compile代码，

model.compile(loss=weighted_binary_crossentropy, run_eagerly = True, optimizer='adam', metrics=['accuracy'])

固定代码 -

%tensorflow_version 2.x
import tensorflow as tf
print(tf.__version__)
import numpy as np
from numpy import loadtxt
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense
from tensorflow.keras import backend as K

print("tf.executing_eagerly() Results")
print("Before loading dataset :",tf.executing_eagerly())

# load pima indians dataset
dataset = np.loadtxt("/content/pima-indians-diabetes.csv", delimiter=",")

# split into input (X) and output (Y) variables
X = dataset[:,0:8]
Y = dataset[:,8]

# define model
model = Sequential()
model.add(Dense(12, input_dim=8, activation='relu'))
model.add(Dense(8, activation='relu'))
model.add(Dense(1, activation='sigmoid'))

print("After building model :",tf.executing_eagerly())

def weighted_binary_crossentropy(y_true, y_pred):
  print("In loss function :",tf.executing_eagerly())
  return K.mean(K.binary_crossentropy(y_pred, y_true))

# compile model
model.compile(loss=weighted_binary_crossentropy, run_eagerly = True, optimizer='adam', metrics=['accuracy'])

print("After compiling model :",tf.executing_eagerly())

# Fit the model
model.fit(X, Y, epochs=1, batch_size=150, verbose=0)

# evaluate the model
scores = model.evaluate(X, Y, verbose=0)
print("%s: %.2f%%" % (model.metrics_names[1], scores[1]*100))

输出 -

2.2.0
tf.executing_eagerly() Results
Before loading dataset : True
After building model : True
After compiling model : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
In loss function : True
accuracy: 34.90%

希望这能回答你的问题。快乐学习。

于 2020-05-18T08:06:28.630 回答