python 如何将输入值转换为数学 function

Question

How to convert an input value into a function!

x = int(input('Enter x value: '))
n = str(input('Enter n value: ')) #n= 2 * x ^ 2 - 2 * x + 2
def f(x,n):
    return 2 * x ^ 2 - 2 * x + 2

Answer 1

Actually for what i understand, you don't need to input n.

x = int(input('Enter x value: '))
def f(x):
    return 2*x**2 - 2*x+2

n = f(x)

Edit, after rereading others answer yes it probably wanted eval() Just You can't write "2 * x ^ 2 - 2 * x + 2", the correct way is x**2 instead of x^2

Answer 2

You mean (?):

def f(x, n):
    return n*x**2 - 2*x + 2

Or do you mean actually changing the operators?

The question as currently posed is mathematically impossible. You define x & n and are returning a function that you may or may not want to equate to n but its all defined entries.

Still guessing a little at the actual question, but if

y = input("Enter equation to evaluate")

and you expect y to be a quadratic, ie:

y = "a*x**b - c*x + d"

then you can get all them from:

import re
y1 = re.split('[* ]',y)

a = y1[0]
b = y1[3]  #as there is a null ent between the ** we skip y1[2] and y[1] is 'x'
c = y1[5]
d = y1[8]

If you wanted the operators, then it gets a little harder to follow. So we'll cross that bridge if you do need them.

Or, as the others suggest, just use eval()!!

Answer 3

You could try to use eval .

x=int(input('...'))
n=input('...') # note that input returns a string

def f(x):
   global n
   return(eval(n))

Answer 4

I think,you are asking. How to convert an input value into a mathmetical expression?

If it is so !

use eval() in python