Preventing evaluation of boolean logic operators
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Vincent Noel
Mar 8, 2016, 4:35:46 PM3/8/16
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Hi !
I'm working on a project where I need to save expressions unevaluated. So far so good, but I'm having a problem with boolean operators.
Here is an example of expression (coming from test units, thus the apparent weirdness) :
True && False
which I'm writing in Sympy as :
sympy.And(sympy.true, sympy.false, evaluate=False)
Problem is that, contrary to other sympy operators/functions, the evaluate=False seems to have no effect. This always evaluate the expression
Is there any other way to prevent that ? Am I doing something wrong ?
Many thanks for what is already an awesome library :)
Vincent
I'm working on a project where I need to save expressions unevaluated. So far so good, but I'm having a problem with boolean operators.
Here is an example of expression (coming from test units, thus the apparent weirdness) :
True && False
which I'm writing in Sympy as :
sympy.And(sympy.true, sympy.false, evaluate=False)
Problem is that, contrary to other sympy operators/functions, the evaluate=False seems to have no effect. This always evaluate the expression
Is there any other way to prevent that ? Am I doing something wrong ?
Many thanks for what is already an awesome library :)
Vincent
Aaron Meurer
Mar 8, 2016, 4:48:46 PM3/8/16
to sy...@googlegroups.com
I think the evaluation of booleans happens in the superclass
(LatticeOp), which ignores the evaluate flag. It should probably be
considered a bug. A simple workaround would be to use Symbol("true")
and Symbol("false") instead of S.true and S.false (and replace them
with their true boolean counterparts when you wish to evaluate them).
Aaron Meurer
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(LatticeOp), which ignores the evaluate flag. It should probably be
considered a bug. A simple workaround would be to use Symbol("true")
and Symbol("false") instead of S.true and S.false (and replace them
with their true boolean counterparts when you wish to evaluate them).
Aaron Meurer
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> Visit this group at https://groups.google.com/group/sympy.
> To view this discussion on the web visit
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> For more options, visit https://groups.google.com/d/optout.
Vincent Noel
Mar 9, 2016, 1:16:14 PM3/9/16
to sympy
Many thanks Aaron !
What would be the best place to do a bug report ? Github ?
Vincent
What would be the best place to do a bug report ? Github ?
Vincent
Sartaj Singh
Mar 9, 2016, 2:08:01 PM3/9/16
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> What would be the best place to do a bug report ? Github ?
Yes, we have our bug tracker on github. File an issue [here](https://github.com/sympy/sympy/issues).
To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/49a3047a-347e-4299-a1a2-c2cda27eef5a%40googlegroups.com.
Regards
Sartaj Singh
Mathematics and Computing,
Indian Institute of Technology,
Varanasi - 221 005 INDIA
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