defined loss function in tensorflow? -

in project, negative instance far more positive instance, want give positive instance larger weight. target is:

loss = 0.0 if y_label==1:loss += 100 * cross_entropy else:loss += cross_entropy 

how realizate in tensorflow[?]

let losses vector (rank-1 tensor) of loss values examples in batch. , let y the vector of corresponding labels. achieve result want by

weights = w_pos*y + w_neg*(1.0-y) loss = tf.reduce_mean(weights*losses) 

here, w_pos , w_neg constant scalar values (w_pos=100.0 , w_neg=1.0 in example). vector weights has value of w_pos examples label equals 1 , w_neg equals 0. multiply weights element-wise losses weigh values in losses according corresponding labels , take mean.