Re: [MLlib][Test] Smoke and Metamorphic Testing of MLlib

2018-08-23 Thread Matei Zaharia
Yes, that makes sense, but just to be clear, using the same seed does *not* imply that the algorithm should produce “equivalent” results by some definition of equivalent if you change the input data. For example, in SGD, the random seed might be used to select the next minibatch of examples, but

Re: [MLlib][Test] Smoke and Metamorphic Testing of MLlib

2018-08-23 Thread Erik Erlandson
Behaviors at this level of detail, across different ML implementations, are highly unlikely to ever align exactly. Statistically small changes in logic, such as "<" versus "<=", or differences in random number generators, etc, (to say nothing of different implementation languages) will accumulate o

Re: [MLlib][Test] Smoke and Metamorphic Testing of MLlib

2018-08-23 Thread Steffen Herbold
Dear Matei, thanks for the feedback! I used the setSeed option for all randomized classifiers and always used the same seeds for training with the hope that this deals with the non-determinism. I did not run any significance tests, because I was considering this from a functional perspective,

Re: [MLlib][Test] Smoke and Metamorphic Testing of MLlib

2018-08-22 Thread Matei Zaharia
Hi Steffen, Thanks for sharing your results about MLlib — this sounds like a useful tool. However, I wanted to point out that some of the results may be expected for certain machine learning algorithms, so it might be good to design those tests with that in mind. For example: > - The classific

Re: [MLlib][Test] Smoke and Metamorphic Testing of MLlib

2018-08-22 Thread Sean Owen
Certainly if your tests have found a problem, open a JIRA and/or pull request with the fix and relevant tests. More tests generally can't hurt, though I guess we should maybe have a look at them first. If they're a lot of boilerplate and covering basic functions already covered by other tests, the