Best way to isolate one coefficient of a multivariate polynomial in sympy

Question

I have a multivariate polynomial (which in the general case many many variables) whose coefficients list some data that I need to read off, but it doesn\'t seem like sympy g

Answer 1

The documentation of polynomial module lists plenty of ways to handle coefficients. For example:

>>> import sympy
>>> x,y,z = sympy.symbols('x,y,z')
>>> p = sympy.poly((x+2*y-z)**3)
>>> p.coeffs()
[1, 6, -3, 12, -12, 3, 8, -12, 6, -1]

These are nonzero coefficients in lexicographic order. To see the monomials in matching order, use

>>> p.monoms()
[(3, 0, 0), (2, 1, 0), (2, 0, 1), (1, 2, 0), (1, 1, 1), (1, 0, 2), (0, 3, 0), (0, 2, 1), (0, 1, 2), (0, 0, 3)]

To get the coefficient of a particular monomial, use

>>> p.coeff_monomial(x**2*y)
6