[GitHub] szha commented on issue #8027: Optional reshape of predictions in Perplexity metric

2018-01-22 Thread GitBox
szha commented on issue #8027: Optional reshape of predictions in Perplexity 
metric
URL: https://github.com/apache/incubator-mxnet/pull/8027#issuecomment-359669294
 
 
   Yes, I was looking into the metrics, and I didn't feel like having a 
separate perplexity metric was necessary in gluon. The reason is that 
perplexity is usually just the exp(cross_entropy_loss). Since 
cross_entropy_loss is required for training and often used in testing, getting 
perplexity is just about calculating its exponential. Having a separate 
perplexity in that case could mean unnecessarily repeated computation.
   
   Our separation of metric and loss was an artifact of past design choices. 
Given that gluon.loss already covers many metrics, I'm not sure how much value 
it would add to have a separate metric package. The only case that can be 
useful is for the metrics with non-differentiable calculation, such as those 
involving argmax and topk (acc, P, R, F1, etc.)


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[GitHub] szha commented on issue #8027: Optional reshape of predictions in Perplexity metric

2018-01-22 Thread GitBox
szha commented on issue #8027: Optional reshape of predictions in Perplexity 
metric
URL: https://github.com/apache/incubator-mxnet/pull/8027#issuecomment-359669294
 
 
   Yes, I was looking into the metrics, and I didn't feel like having a 
separate perplexity metric was necessary in gluon. The reason is that 
perplexity is usually just the exp(cross_entropy_loss). Since 
cross_entropy_loss is required for training and often used in testing, getting 
perplexity is just about calculating its exponential. Having a separate 
perplexity in that case could mean unnecessarily repeated computation.


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