CODEWITHSUNDEEP
pythonpython-3.xsympy
Zelnoth
Zelnoth

Reputation: 164

Sympy: Using logical operators on relationals

Is this possible? What I want to do is something like this: sympify('2>1 | 2<1')

I pretty much only need 'or' and 'and'. I also tried doing sympify('2>1') | sympify('2<1'). Ideally I would want to just be able to send in a string with relations and logical operators to a function and have it return true or false. (i.e. '(2>1 | 2<1) & 3==3')

Upvotes: 2

Views: 243

Answers (1)

Alex Riley
Alex Riley

Reputation: 176750

The problem is operator precedence in Python/SymPy: you need to surround the inequalities with parentheses otherwise 1 | 2 is evaluated first and an error is raised by SymPy. You can write:

>>> sympify('(2>1) | (2<1)')
True # SymPy bool

Of course, you don't really need SymPy's power for logical expressions just involving & and |. Python's bool type supports the operators although you still need parentheses to ensure the correct result: 

>>> (2>1) | (2<1)
True # Python bool

Upvotes: 2

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