Safer way to sympify unsanitized input
Project description
Safer Sympify
Convert unsanitized user input into SymPy expression.
This does not prevent all possible attacks. However, this is much safer than using eval()
, which SymPy still does.
See SymPy PR12524 for more details: https://github.com/sympy/sympy/pull/12524
Examples
Create a SymPy expression from user input.
This uses pure Python syntax.
Whitelisted operators and functions only are allowed.
>>> expr = SaferSympify().str2sympy('-sqrt(1 + a**b*b)/((a**b)*b+1)')
>>> expr
-1/sqrt(a**b*b + 1)
Get free symbols:
>>> sorted(expr.free_symbols, key=lambda x: str(x))
[a, b]
Evaluate expression:
>>> expr.evalf(subs={'a': 1, 'b': 3, 'c': 5}) # Note extra values can be passed too
-0.500000000000000
Simplify expression:
>>> expr.simplify()
-1/sqrt(a**b*b + 1)
Pretty-print expression as Latex (could be displayed in browser with MathJax)
>>> sympy.latex(expr)
'- \\frac{1}{\\sqrt{a^{b} b + 1}}'
Pretty-print in terminal
>>> sympy.pprint(expr, use_unicode_sqrt_char=True)
-1
─────────────
__________
╱ b
╲╱ a ⋅b + 1
Project details
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