List of coefficients to polynomial

问题

How do I create a polynomial out of a list of coefficients in SymPy?

For example, given a list [1, -2, 1] I would like to get Poly(x**2 - 2*x + 1). I tried looking at the docs but could not find anything close to it.

回答1:

You could use Poly.from_list to construct the polynomial:

>>> x = sympy.Symbol('x')
>>> sympy.Poly.from_list([1, -2, 1], gens=x)
Poly(x**2 - 2*x + 1, x, domain='ZZ')

回答2:

It looks to me like you would do something like:

from sympy.abc import x
from sympy import poly
lst = [1, -2, 1]
poly(sum(coef*x**i for i, coef in enumerate(reversed(lst))))

Of course, you don't depending on which coefficient maps to x**0, you might not need the reversed in the above.

回答3:

This simpler alternative works for me (Sympy 0.7.6.1):

>>> from sympy import Symbol, Poly
>>> x = Symbol('x')
>>> Poly([1,2,3], x)
Poly(x**2 + 2*x + 3, x, domain='ZZ')

来源：https://stackoverflow.com/questions/32406651/list-of-coefficients-to-polynomial