How to create a layer to invert a softmax (TensforFlow,python)?

Question

I am building a deconvolution network. I would like to add a layer to it which is the reverse of a softmax. I tried to write a basic python function that returns the inverse of

Answer 1

Thanks it works ! I put :

import keras.backend as K

def inv_softmax(x,C):
   return K.log(x)+K.log(C)

Answer 2

Try this:

import tensorflow as tf

def inv_softmax(x, C):
   return tf.math.log(x) + C

import math
input = tf.keras.layers.Input(shape=(1,10))
x = tf.keras.layers.Lambda(lambda x : inv_softmax(x, math.log(10.)),name='inv_softmax')(input)
model = tf.keras.Model(inputs=input, outputs=x)

a = tf.zeros([1, 1, 10])
a = tf.nn.softmax(a)
a = model(a)
print(a.numpy())