We all know that math notation is idiosyncratic. Canonical representation of math objects often have irregular grammar rules to improve readability. For example we write a polynomial \3ドルx^3 + x^2\$ instead of more uniform but more verbose \3ドルx^3 + 1x^2 + 0x^1 + 0x^0\$. When a coefficient equals 0, you don't write the term, if the power equals \1ドル\$, you simply write \$x\$, and so on. So I wrote a simple program that outputs a string representation of a polynomial, given a list of coefficients:
def enumerate2(xs, start=0, step=1):
for x in xs:
yield (start, x)
start += step
def poly(xs):
"""Return string representation of a polynomial.
>>> poly([2,1,0])
"2x^2 + x"
"""
res = []
for e, x in enumerate2(xs, len(xs)-1, -1):
variable = 'x'
if x == 1:
coefficient = ''
elif x == -1:
coefficient = '-'
else:
coefficient = str(x)
if e == 1:
power = ''
elif e == 0:
power = ''
variable = ''
else:
power = '^' + str(e)
if x < 0:
coefficient = '(' + coefficient
power = power + ')'
if x != 0:
res.append(coefficient + variable + power)
return ' + '.join(res)
enumerate2 is a custom version of enumerate that supports variable step supports variable step. The result looks like this:
>>> poly([2,0,3,-4,-3,2,0,1,10])
'2x^8 + 3x^6 + (-4x^5) + (-3x^4) + 2x^3 + x + 10'
How do I make this code more elegant and probably more generic? Oh, and the result is sub-optimal, as negative terms are enclosed in brackets, instead of changing the preceding plus sign to minus.
We all know that math notation is idiosyncratic. Canonical representation of math objects often have irregular grammar rules to improve readability. For example we write a polynomial \3ドルx^3 + x^2\$ instead of more uniform but more verbose \3ドルx^3 + 1x^2 + 0x^1 + 0x^0\$. When a coefficient equals 0, you don't write the term, if the power equals \1ドル\$, you simply write \$x\$, and so on. So I wrote a simple program that outputs a string representation of a polynomial, given a list of coefficients:
def enumerate2(xs, start=0, step=1):
for x in xs:
yield (start, x)
start += step
def poly(xs):
"""Return string representation of a polynomial.
>>> poly([2,1,0])
"2x^2 + x"
"""
res = []
for e, x in enumerate2(xs, len(xs)-1, -1):
variable = 'x'
if x == 1:
coefficient = ''
elif x == -1:
coefficient = '-'
else:
coefficient = str(x)
if e == 1:
power = ''
elif e == 0:
power = ''
variable = ''
else:
power = '^' + str(e)
if x < 0:
coefficient = '(' + coefficient
power = power + ')'
if x != 0:
res.append(coefficient + variable + power)
return ' + '.join(res)
enumerate2 is a custom version of enumerate that supports variable step. The result looks like this:
>>> poly([2,0,3,-4,-3,2,0,1,10])
'2x^8 + 3x^6 + (-4x^5) + (-3x^4) + 2x^3 + x + 10'
How do I make this code more elegant and probably more generic? Oh, and the result is sub-optimal, as negative terms are enclosed in brackets, instead of changing the preceding plus sign to minus.
We all know that math notation is idiosyncratic. Canonical representation of math objects often have irregular grammar rules to improve readability. For example we write a polynomial \3ドルx^3 + x^2\$ instead of more uniform but more verbose \3ドルx^3 + 1x^2 + 0x^1 + 0x^0\$. When a coefficient equals 0, you don't write the term, if the power equals \1ドル\$, you simply write \$x\$, and so on. So I wrote a simple program that outputs a string representation of a polynomial, given a list of coefficients:
def enumerate2(xs, start=0, step=1):
for x in xs:
yield (start, x)
start += step
def poly(xs):
"""Return string representation of a polynomial.
>>> poly([2,1,0])
"2x^2 + x"
"""
res = []
for e, x in enumerate2(xs, len(xs)-1, -1):
variable = 'x'
if x == 1:
coefficient = ''
elif x == -1:
coefficient = '-'
else:
coefficient = str(x)
if e == 1:
power = ''
elif e == 0:
power = ''
variable = ''
else:
power = '^' + str(e)
if x < 0:
coefficient = '(' + coefficient
power = power + ')'
if x != 0:
res.append(coefficient + variable + power)
return ' + '.join(res)
enumerate2 is a custom version of enumerate that supports variable step. The result looks like this:
>>> poly([2,0,3,-4,-3,2,0,1,10])
'2x^8 + 3x^6 + (-4x^5) + (-3x^4) + 2x^3 + x + 10'
How do I make this code more elegant and probably more generic? Oh, and the result is sub-optimal, as negative terms are enclosed in brackets, instead of changing the preceding plus sign to minus.