如何從 python 中的字符串中提取數學方程式？

Question

我對數學方程式和字符串有疑問。 如果用戶給出字符串格式的數學方程式，我如何從字符串中獲取它並計算值？

Input: 
x = 1
y = 2
formula = "x+y"
Output:
formula = x+y
formula = 3

Answer 1

>>> x, y = 1, 2
>>> formula = "x+y"
>>> print('formula = ' + formula)
formula = x+y
>>> print('formula = ' + str(eval(formula)))
formula = 3