Addons: Problem with using Tensorflow addons' metrics correctly in functional API

[JoBerkner]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Windows 10 / Google Colab
• TensorFlow version and how it was installed (source or binary): 2.1.0-rc1 (pip install)
• TensorFlow-Addons version and how it was installed (source or binary): 0.6.0 (pip install)
• Python version: 3.6.9
• Is GPU used? (yes/no):

Describe the bug

I have an LSTM model to perform binary classification of human activities using multivariate smartphone sensor data. The two classes are imbalanced (1:50). Therefore I would like to use F1-score as a metric, which is why I came across the TensorFlow Addons.

I now have a problem to apply this score to my functional API.
If I use another value for the metric argument average (e.g., average=None or average="macro") then I get an error message when fitting the model:

ValueError: Dimension 0 in both shapes must be equal, but are 2 and 1. Shapes are [ 2 ] and [ 1 ]. for 'AssignAddVariableOp' (op: 'AssignAddVariableOp') with input shapes: [ ], [ 1 ].

And if I use the value average="micro" I am not getting the error, but the F1-score is 0 throughout the learning process, while my loss decreases.

I believe I am still doing something wrong here. Can anybody provide an explanation for me?

Code to reproduce the issue

import tensorflow as tf 
import tensorflow_addons as tfa
from tensorflow import kerasdef

create_model(n_neurons=150, learning_rate=0.01, activation="relu", loss="binary_crossentropy"):

   #create input layer and assign to current output layer
   input_ = keras.layers.Input(shape=(X_train.shape[1],X_train.shape[2])) 

   #add LSTM layer
   lstm = keras.layers.LSTM(n_neurons, activation=activation)(input_)

   #Output Layer
   output = keras.layers.Dense(1, activation="sigmoid")(lstm)

   #Create Model
   model = keras.models.Model(inputs=[input_], outputs=[output])

   #Add optimizer
   optimizer=keras.optimizers.SGD(lr=learning_rate, clipvalue=0.5)

   #Compile model
   model.compile(loss=loss, optimizer=optimizer, metrics=[tfa.metrics.F1Score(num_classes=2, average="micro")])

   print(model.summary())

   return model

#Create the model
model = create_model()

#fit the model
history = model.fit(X_train,y_train, 
                epochs=300, 
                validation_data=(X_val, y_val))

Other info / logs

[Squadrick]

cc code owner @SSaishruthi

[SSaishruthi]

Will check

[SSaishruthi]

@seanpmorgan I am not seeing threshold parameters in the current release. It is throwing an error when using it. Below is the screenshot of the same. Any idea why?

This issue can be solved by that

[Squadrick]

The newer version of F-scores from #502 isn't included in r0.6 (the older version is included). Installing tfa-nightly should include the F-scores with threshold.

[SSaishruthi]

Thanks, @Squadrick.

I will post the solution here using nightly version

[tillmo]

There are two other problems here:

1. the model uses binary classification, but f1-score in tfa assumes categorical classification with one-hot encoding, see https://github.com/tensorflow/addons/issues/746#issuecomment-562963134

2. f1-score is called at each batch step at validation. This does not make sense. The right way to do this is to use a custom callback function in a way like this: https://github.com/PhilipMay/mltb/blob/7fce1f77294dccf94f6d4c65b2edd058a654617b/mltb/keras.py. See also https://medium.com/@thongonary/how-to-compute-f1-score-for-each-epoch-in-keras-a1acd17715a2. I have filed an issue: #825