Python中的文本到数学方程

Question

I'm writing now a pet project in which I want to draw a plot in the terminal window. The idea is that user print an equation, like x = y + 1 , or 3 * x = y . The question is how can I transfer this string equation to an equation in Python.

For instance: I have an array, for x values like:

x_arr = [1, 2, 3, 4, 5]

And then I want to put it into the user's equation to get y values. or vise versa (vise versa, put y values to get x values)

Thought to create a lot of if conditions and use for loop to detect every character but it seems something like a sandbox. Is there a more elegant way?

Answer 1

You can do it using sympy library.

      from sympy import *
      from sympy.solvers import solve
      x,y = symbols('x,y')
      eq = '3*x=y*2'
      parts = [x.strip() for x in eq.split('=')]
      final_eq = parts[1]+'-({})'.format(parts[0])
      equation = Eq(eval(parts[0]),eval(parts[1]))
      x_array = [1,2,3,4,5]
      for x1 in x_array:
            print('given x={}, y={}'.format(x1,solve(equation.subs(x,x1),y)))

Ouput

      given x=1, y=[3/2]
      given x=2, y=[3]
      given x=3, y=[9/2]
      given x=4, y=[6]
      given x=5, y=[15/2]

Answer 2

Use eval for evaluating the textual commands.

https://www.programiz.com/python-programming/methods/built-in/eval