def padded_neg_log_perplexity(logits, labels, vocab_size):
    'Average log-perplexity excluding padding 0s. No smoothing.'
    (num, den) = padded_cross_entropy_loss(logits, labels, 0, vocab_size)
    return ((- num), den)
Average log-perplexity excluding padding 0s. No smoothing.
def padded_neg_log_perplexity(logits, labels, vocab_size):
    
    (num, den) = padded_cross_entropy_loss(logits, labels, 0, vocab_size)
    return ((- num), den)