借助sympy.sympify()方法
示例1
from sympy import sympify
converter = {
'sub': lambda x, y: x - y,
'div': lambda x, y: x / y,
'mul': lambda x, y: x * y,
'add': lambda x, y: x + y,
'neg': lambda x: -x,
'pow': lambda x, y: x ** y
}
formula = sympify( txt, locals=converter)
print(formula)
示例2
\# Import sympy
from sympy import *
\# Define symbols and trigo expression
x, y = symbols('x y')
expn = "x**2 + 3 * x - 1 / 2"
\# Use sympy.sympify() method
gfg = sympify(expn)
gfg = gfg.subs(x, 3)
print(gfg)