Re: dict to boolean expression, how to?

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From	Roy Smith <roy@panix.com>
Newsgroups	comp.lang.python
Subject	Re: dict to boolean expression, how to?
Date	Fri, 01 Aug 2014 09:24:48 -0400
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In article <53db8bd8$0$2976$e4fe514c@news2.news.xs4all.nl>,
 Alex van der Spek <zdoor@xs4all.nl> wrote:

> With a dict like so:
> 
> cond = {'a': 1, 'b': 1, 'c': 1,
>         'A': 0, 'B', 0, 'C':0}
> 
> how would you make a boolean expression like this:
> 
> bool = (('a' == 1) & ('A' == 0) |
>         ('b' == 1) & ('B' == 0) |
>         ('c' == 1) & ('C' == 0))
> 
> The fact that lowercase and uppercase keys are stringed together with & is 
> intentional albeit the actual condition is a bit more tricky.
> 
> I've tried several approaches using eval() on a string built from the dict 
> but landed with just spelling it out literally.

I would certainly avoid eval(), especially if there's any chance 
(including ways you can't possibly imagine right now) of external data 
getting included.  Google for "little bobby tables".

Maybe something like (coding on the fly, not tested):

terms = []
for key in 'abc':
    term = cond[key] and not cond[key.upper()]
    terms.append(term)

bool_value = any(terms)

Thread

dict to boolean expression, how to? Alex van der Spek <zdoor@xs4all.nl> - 2014-08-01 12:45 +0000
  Re: dict to boolean expression, how to? Chris Angelico <rosuav@gmail.com> - 2014-08-01 23:04 +1000
  Re: dict to boolean expression, how to? Roy Smith <roy@panix.com> - 2014-08-01 09:24 -0400
  Re: dict to boolean expression, how to? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-01 13:28 +0000
    Re: dict to boolean expression, how to? Roy Smith <roy@panix.com> - 2014-08-01 09:32 -0400
      Re: dict to boolean expression, how to? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-01 15:02 +0000
        Re: dict to boolean expression, how to? Terry Reedy <tjreedy@udel.edu> - 2014-08-01 18:16 -0400
    Re: dict to boolean expression, how to? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-01 16:50 +0100
      Re: dict to boolean expression, how to? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-01 16:35 +0000
  Re: dict to boolean expression, how to? Alex van der Spek <zdoor@xs4all.nl> - 2014-08-01 14:26 +0000
    Re: dict to boolean expression, how to? marco.nawijn@colosso.nl - 2014-08-01 08:07 -0700
    Re: dict to boolean expression, how to? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-01 15:24 +0000
      Re: dict to boolean expression, how to? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-01 17:03 +0100
    Re: dict to boolean expression, how to? Peter Otten <__peter__@web.de> - 2014-08-01 17:44 +0200
      eval [was Re: dict to boolean expression, how to?] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-02 02:59 +0000
        Re: eval [was Re: dict to boolean expression, how to?] Peter Otten <__peter__@web.de> - 2014-08-02 09:43 +0200
        Re: eval [was Re: dict to boolean expression, how to?] Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-02 08:59 +0100
        Re: eval [was Re: dict to boolean expression, how to?] Duncan Booth <duncan.booth@invalid.invalid> - 2014-08-05 11:57 +0000
          Re: eval [was Re: dict to boolean expression, how to?] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-06 02:25 +1000
    Re: dict to boolean expression, how to? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-01 17:12 +0100
    Re: dict to boolean expression, how to? Peter Pearson <ppearson@nowhere.invalid> - 2014-08-01 17:00 +0000
  Re: dict to boolean expression, how to? Ned Batchelder <ned@nedbatchelder.com> - 2014-08-01 10:29 -0400

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