Re: NaN comparisons - Call For Anecdotes

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From	Johann Hibschman <jhibschman@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: NaN comparisons - Call For Anecdotes
Date	Thu, 17 Jul 2014 11:12:28 -0400
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"Anders J. Munch" <2014@jmunch.dk> writes:
> So far I received exactly the answer I was expecting.  0 examples of
> NaN!=NaN being beneficial.
> I wasn't asking for help, I was making a point.  Whether that will
> lead to improvement of Python, well, I'm not too optimistic, but I
> feel the point was worth making regardless.

Well, I just spotted this thread.  An easy example is, well, pretty much
any case where SQL NULL would be useful.  Say I have lists of borrowers,
the amount owed, and the amount they paid so far.

    nan = float("nan")
    borrowers = ["Alice", "Bob", "Clem", "Dan"]
    amount_owed = [100.0, nan, 200.0, 300.0]
    amount_paid = [100.0, nan, nan, 200.0]
    who_paid_off = [b for (b, ao, ap) in
                          zip(borrowers, amount_owed, amount_paid)
                      if ao == ap]

I want to just get Alice from that list, not Bob.  I don't know how much
Bow owes or how much he's paid, so I certainly don't know that he's paid
off his loan.

Cheers,
Johann

Thread

Re: NaN comparisons - Call For Anecdotes "Anders J. Munch" <2014@jmunch.dk> - 2014-07-10 01:03 +0200
  Re: NaN comparisons - Call For Anecdotes Johann Hibschman <jhibschman@gmail.com> - 2014-07-17 11:12 -0400
    Re: NaN comparisons - Call For Anecdotes Chris Angelico <rosuav@gmail.com> - 2014-07-18 01:36 +1000
      Re: NaN comparisons - Call For Anecdotes Johann Hibschman <jhibschman@gmail.com> - 2014-07-17 14:49 -0400
        Re: NaN comparisons - Call For Anecdotes Chris Angelico <rosuav@gmail.com> - 2014-07-18 04:55 +1000
          Re: NaN comparisons - Call For Anecdotes Marko Rauhamaa <marko@pacujo.net> - 2014-07-17 22:10 +0300
            Re: NaN comparisons - Call For Anecdotes Ian Kelly <ian.g.kelly@gmail.com> - 2014-07-17 14:39 -0600
              Re: NaN comparisons - Call For Anecdotes Marko Rauhamaa <marko@pacujo.net> - 2014-07-18 00:08 +0300
                Re: NaN comparisons - Call For Anecdotes Ian Kelly <ian.g.kelly@gmail.com> - 2014-07-17 17:00 -0600
                Re: NaN comparisons - Call For Anecdotes Ian Kelly <ian.g.kelly@gmail.com> - 2014-07-17 17:07 -0600
        Re: NaN comparisons - Call For Anecdotes Chris Angelico <rosuav@gmail.com> - 2014-07-18 04:59 +1000
      Re: NaN comparisons - Call For Anecdotes Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-07-18 17:57 +0000
        Re: NaN comparisons - Call For Anecdotes Chris Angelico <rosuav@gmail.com> - 2014-07-19 05:49 +1000

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