polynomial_extract.py

#!/usr/bin/env python
import re, sys

def seperate(e):
	"""seperate the equalization:
	eg. 2x^2+3x-2 -> ["2x^2", "3x", "-2"]"""
	s = re.split(r"([+-])", e)
	opt = []
	nextMinus=False
	if s[0] == "":
		s = s[1:]
	for i in range(len(s)):
		if s[i] not in ("+", "-"):
			a=s[i]
			if nextMinus:
				a="-"+a	
				nextMinus = False
			opt.append(a)
		else:
			if s[i] == "-":
				nextMinus = True
	return opt
def writeWithSign(num):
	if num > 0:
		return "+"+str(num)
	else:
		return str(num)
def getDegree(s):
	degree =  re.findall(r"^([\-0-9]+)", s)
	if not degree:
		return 1
	else:
		if degree[0] == "-":
			return 1
		return int(degree[0])
def getVar(s):
	var = re.findall("([a-zA-Z]+)", s)
	try:
		return var[0]
	except IndexError:
		return "x"
def extract(s, eq="N/A"):
	degrees = []
	var = getVar(s[0])
	# 1 -> find the degree
	degrees.append(getDegree(s[0]))
	degrees.append(getDegree(s[2]))
	# 2 -> find the second degree
	target = getDegree(s[1])
	# 3 -> brute force!
	found = None
	sides = []
	if degrees[0] < 0:
		sides.append(-1)
	else:
		sides.append(1)
	if degrees[1] < 0:
		sides.append(-1)
	else:
		sides.append(1)
	for i in xrange(sides[0], degrees[0]+sides[0], sides[0]):
		if found != None:
			break
		i2 = float(degrees[0])/float(i)
		if i2 != int(i2):
			continue
		sys.stderr.write(`i`+" "+`i2`+"\n")
		for j in xrange(1, abs(degrees[1])+1):
			j2 = float(degrees[1])/float(j)
			if j2 != int(j2):
				continue
			sys.stderr.write("-> "+`j`+" "+`j2`+"\n")
			sys.stderr.write("--> "+`abs(j)*-1`+" "+`abs(j2)*-1`+" "+`degrees[1] == abs(degrees[1])`+"\n")
			if (i * j)+(i2 * j2) == float(target):
				found = [[i, i2], [j, j2]]
				break
			elif (i * (abs(j)*-1))+(i2 * (abs(j2)*-1)) == float(target) and degrees[1] == abs(degrees[1]):
				found = [[i, i2], [abs(j)*-1, abs(j2)*-1]]
				break
			elif ((abs(i)*-1) * (abs(j)*-1))+((abs(i2)*-1) * (abs(j2)*-1)) == float(target) and degrees[1] == abs(degrees[1]):
				found = [[(abs(i)*-1), (abs(i2)*-1)], [abs(j)*-1, abs(j2)*-1]]
				break
			elif ((abs(i)*-1) * j)+((abs(i2)*-1) * j2) == float(target) and degrees[1] == abs(degrees[1]):
				found = [[(abs(i)*-1), (abs(i2)*-1)], [j, j2]]
				break
			#else:
			#	print "Not "+`target`+": "+`[[i, i2], [j, j2]]`
	# 4 -> now cross and show the output
	out = ""
	out +=  "%s:\t%s\t->\t%s\t%s\n\t\t%s\t->\t%s\t%s\n"%(
		eq, degrees[0], found[0][0], found[0][1],
		degrees[1], found[1][0], found[1][1]
	)
	if found[0][0] == 1:
		found[0][0] = ""
	else:
		found[0][0] = int(found[0][0])
	if found[0][1] == 1:
		found[0][1] = ""
	else:
		found[0][1] = int(found[0][1])
	out += "%s:\t(%s%s%s)(%s%s%s)\n"%(
		eq, found[0][0], var,
		writeWithSign(int(found[1][1])), found[0][1], var,
		writeWithSign(int(found[1][0])))
	return out

if __name__ == "__main__":
	if len(sys.argv) > 1:
		eq = [sys.argv[1]]
	else:
		eq = [
			'2x^2+5x+2',
			'2x^2+5x-3',
			'2x^2+5x-12',
			'3x^2+19x-40',
			'9x^2-42x+49',
			'12x^2-25x+7',
			'16x^2+88x+121',
			'3x^2+19x+6',
			'2x^2-x-6',
			'11x^2-12x-20',
			'3x^2-16x+16',
			'12x^2-23x+5',
			'7x^2-40x-12',
			'24x^2-13x-2',
			'13x^2-16x-20',
			'6x^2-x-12',
			'81x^2+0-169',
			'8x^2-34x+33',
			'8x^2-34x+21',
			'12x^2+8x-7',
			'6x^2+7x-3',
			'-18x^2+3x+28',
			'-10x^2-11x+6',
			'8x^2+2x-15',
		]
		# another set
		eq += [
			'-36x^2+19x+6',
			'-12x^2-x+6',
			'40x^2-50x-35',
			'3x^2+30x+75',
			'3x^2-6x-9',
			'9y^2-6y+1',
			'6a^2+a-12',
			'12a^2+41a+35',
			'12a^2-a-35',
			'-12a^2-a+35',
			'5x^2+4x-1',
			'12x^2-107x-9',
			'35m^2+18m-8',
			'x^2-7x+6',
			'49y^2-42y+9',
			'16x^2-8x+1',
			'-3z^2+2z+5',
			'15x^2+8x-7',
			'6x^2+31x-52',
			'25z^2+0-121',
			'9x^2-12x-5',
			#'4x^2+16x-2', #bug!
			'-6x^2+10x+4',
			'3b^2-26b+35',
			'12x^2+0-75',
			'6a^2+17a+12',
			'6a^2-a-12',
		]
	for e in eq:
		s = seperate(e)
		print extract(s, e)