Printing a polynomial in python

Question

I\'m making a Polynomial python class and as part of that, I need to print a polynomial nicely. The class is given a list that represents the coefficients of the polynomial

Answer 1

Here's very simple approach of iterating over coeffs, building string chunk by chunk and joining it afterwards.

class Polynomial:
    def __init__(self, coefficients):
        self.coeffs = coefficients

    def __str__(self):
        chunks = []
        for coeff, power in zip(self.coeffs, range(len(self.coeffs) - 1, -1, -1)):
            if coeff == 0:
                continue
            chunks.append(self.format_coeff(coeff))
            chunks.append(self.format_power(power))
        chunks[0] = chunks[0].lstrip("+")
        return ''.join(chunks)

    @staticmethod
    def format_coeff(coeff):
        return str(coeff) if coeff < 0 else "+{0}".format(coeff)

    @staticmethod
    def format_power(power):
        return 'x^{0}'.format(power) if power != 0 else ''


assert str(Polynomial([2, -3, 0, 5])) == "2x^3-3x^2+5"