# Source code for example_code.polynomial

from numbers import Number
[docs]class Polynomial:
def __init__(self, coefs):
self.coefficients = coefs
[docs] def degree(self):
return len(self.coefficients) - 1
def __str__(self):
coefs = self.coefficients
terms = []
# Degree 0 and 1 terms conventionally have different representation.
if coefs[0]:
terms.append(str(coefs[0]))
if self.degree() > 0 and coefs[1]:
terms.append(f"{coefs[1]}x")
# Remaining terms look like cx^d, though factors of 1 are dropped.
terms += [f"{'' if c == 1 else c}x^{d}"
for d, c in enumerate(coefs[2:], start=2) if c]
# Sum polynomial terms from high to low exponent.
return " + ".join(reversed(terms)) or "0"
def __repr__(self):
return type(self).__name__ + "(" + repr(self.coefficients) + ")"
def __eq__(self, other):
return isinstance(other, Polynomial) and \

self.coefficients == other.coefficients
def __add__(self, other):
if isinstance(other, Number):
return Polynomial((self.coefficients[0] + other,)
+ self.coefficients[1:])
elif isinstance(other, Polynomial):
# Work out how many coefficient places the two polynomials have in
# common.
common = min(self.degree(), other.degree()) + 1
# Sum the common coefficient positions.
coefs = tuple(a + b for a, b in zip(self.coefficients[:common],
other.coefficients[:common]))
# Append the high degree coefficients from the higher degree
# summand.
coefs += self.coefficients[common:] + other.coefficients[common:]
return Polynomial(coefs)
else:
return NotImplemented
def __radd__(self, other):
return self + other