How can I print the values of Keras tensors?

Question

I am implementing own Keras loss function. How can I access tensor values?

What I\'ve tried

def loss_fn(y_true, y_pred):
    print y_true


        

Answer 1

to print the value of a tensor you need the tensor to have value for example:

import tensorflow as tf

aa = tf.constant([1,5,3])
bb = keras.layers.Dense(4, name="my_tensor")
print('aa:',aa)
print('bb:',bb)


aa: tf.Tensor([1 5 3], shape=(3,), dtype=int32)
bb: <tensorflow.python.keras.layers.core.Dense object at 0x000001D4B0137048>

if i want to print b I need to give him a input like this:

aa = tf.constant([[1,5,3]])
bb = keras.layers.Dense(4, name="my_tensor")
print('bb.weights before a assign:',bb.weights,'\n')
print('bb:',bb(aa),'\n')                               
print('bb.weights:',bb.weights)

Output:

bb.weight before a assign: [] 

bb: tf.Tensor([[1.0374807 3.4536252 1.5064619 2.1762671]], shape=(1, 4), dtype=float32) 

bb.weight: [<tf.Variable 'my_tensor/kernel:0' shape=(3, 4) dtype=float32, numpy=
array([[ 0.885918  , -0.88332534, -0.40944284, -0.04479438],
       [-0.27336687,  0.34549594, -0.11853147,  0.15316617],
       [ 0.50613236,  0.8698236 ,  0.83618736,  0.4850769 ]],
      dtype=float32)>, <tf.Variable 'my_tensor/bias:0' shape=(4,) dtype=float32, numpy=array([0., 0., 0., 0.], dtype=float32)>]

If bb is a tensor inside a model or a tensor that the size of the input is fix this will not work

inputs = keras.Input(shape=(3,), name="inputs")
b = keras.layers.Dense(4, name="my_tensor")(inputs)

a = tf.constant([[1,5,3]])
print('b:',b(a),'\n')

Output:

TypeError: 'tensorflow.python.framework.ops.EagerTensor' object is not callable

i use feature_extractor to fix it:

inputs = keras.Input(shape=(3,), name="inputs")
bb = keras.layers.Dense(4, name="my_tensor")(inputs)

feature_extractor = keras.Model(
    inputs=inputs,
    outputs=bb,
)

aa = tf.constant([[1,5,3]])
print('feature_extractor:',feature_extractor(aa),'\n')

Output:

feature_extractor: tf.Tensor([[-4.9181094  4.956725  -1.8055304  2.6975303]], shape=(1, 4), dtype=float32)