ENH: add identity kwarg to frompyfunc #8255
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I created a short script to demonstrate what happens with different identity values. It needs the identity kwarg added in this PR. It shows the get/set value needs work. |
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Haven't looked at this yet, but the enhancement would be useful. |
The only two that are omited are |
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That might make sense. Should I also add a private setter function to convert from input to the internal constants? I think ultimately for some input identity value inp, np.frompyfunc(f, nin, nout, inp).identity == inp (or raise an exception) for all possible values of inp. |
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At the very least, it'd be nice to get the change supporting kwargs to |
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☔ The latest upstream changes (presumably #8861) made this pull request unmergeable. Please resolve the merge conflicts. |
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Seem to me that we first want to overhaul I've a patch |
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#8955 has been merged, @mattharrigan would you like to revive this? |
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Rebased and solved conflicts. Tweaked the |
| types, /* ntypes */ 1, nin, nout, PyUFunc_None, | ||
| str, doc, /* unused */ 0); | ||
| types, /* ntypes */ 1, nin, nout, identity ? PyUFunc_IdentityValue : PyUFunc_None, | ||
| str, doc, /* unused */ 0, NULL, identity); |
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A future PR could add signature, which would help vectorize
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Test added |
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Thank Eric and @mattharrigan. The signature addition has been on my/our "Not Done" list for a bit. Should fairly straight forward, but requires a new slightly different inner loop to handle. |
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@eric-wieser feel free to merge, I think this is good. There are tiny changes in that arguments are now not only positional (which is good). I guess a ping to the mailing list can be good, but since this is a core ufunc feature exposing it to python seems very straight forward. I feel the argument description is a bit difficult, but I cannot figure out how to make it easier. Maybe the link to the ufunc documentation is simply enough. |
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Hmm, seems I could have just merged it back then. I think it is an obvious enough addition to have the |
PR to Close #8245. Adding the kwarg seems pretty straightforward. Understanding what identity actually does is much harder. Several identity constants are defined here. The fact that MinusOne is defined to 2 and None is defined to -1 makes my head hurt. The ufunc getter for identity here seems to have fewer options than what's defined in the earlier link. Finally when I look at the reduce methods they don't make sense to me either. Is there any documentation defining all the possible values for identity and what they mean?
~WIP: ~ (edit by @eric-wieser: rebased and finished)