I'm trying to define a triplet loss using descriptor from a CNN's output, but this error showed up when I try to train the network.
My definition of loss function:
def compute_loss(descriptor, margin):
diff_pos = descriptor[0:1800:3] - descriptor[1:1800:3]
diff_neg = descriptor[0:1800:3] - descriptor[2:1800:3]
Ltriplet = np.maximum(0, 1 - tf.square(diff_neg)/(tf.square(diff_pos) + margin))
Lpair = tf.square(diff_pos)
Loss = Ltriplet + Lpair
return Loss
here descriptor is the outcome of CNN, the income of CNN is a set of triplets containing anchor, puller and pusher exactly in this order. As input I packed 600 triplet together and feed them into the CNN.
Then I got this error when training the network:
2018-03-08 16:40:49.529263: I tensorflow/core/platform/cpu_feature_guard.cc:140] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2 FMA
Traceback (most recent call last):
File "/Users/gaoyingqiang/Documents/GitHub/Master-TUM/TDCV/exercise_3/ex3/task2_new.py", line 78, in <module>
loss = compute_loss(h_fc2, margin)
File "/Users/gaoyingqiang/Documents/GitHub/Master-TUM/TDCV/exercise_3/ex3/task2_new.py", line 37, in compute_loss
Ltriplet = np.maximum(0, 1 - tf.square(diff_neg)/(tf.square(diff_pos) + margin))
File "/Users/gaoyingqiang/.virtualenvs/ex3/lib/python3.6/site-packages/tensorflow/python/framework/ops.py", line 614, in __bool__
raise TypeError("Using a `tf.Tensor` as a Python `bool` is not allowed. "
TypeError: Using a `tf.Tensor` as a Python `bool` is not allowed. Use `if t is not None:` instead of `if t:` to test if a tensor is defined, and use TensorFlow ops such as tf.cond to execute subgraphs conditioned on the value of a tensor.
Process finished with exit code 1
Where goes wrong?
You are mixing numpy and tensorflow operations. Tensorflow accepts numpy arrays normally (their value is known statically, hence can be converted to a constant), but not vice versa (tensor value is known only when the session is run, except eager evaluation).
The solution: change np.maximum
to tf.maximum
.
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