A script for repricing GURPS Character Sheet eqp files per 'After the End' (and some house rules). Mostly I was just proud of the regex.

main.py

import xml.etree.ElementTree as etree
import re
from fractions import Fraction
from math import floor
import sys

tree = etree.parse(sys.argv[1])
output_filename = sys.argv[2]
root = tree.getroot()

all_equipment = root.findall("equipment")

# gets anything that has a ranged_weapon damage, a value, a tech_level and is in the 'Firearms' category.
def get_firearms(equipment):
	for item in equipment:
		categories = [c.text for c in item.findall(".//category")]
		if "Firearms" not in categories:
			continue

		damage = item.find("ranged_weapon/damage")
		value = item.find("value")
		tech_level = item.find("tech_level")

		if damage is None or value is None or tech_level is None:
			continue
		else:
			yield (item, damage, value, tech_level)

def get_valued(equipment):
	for item in equipment:
		value = item.find("value")
		tech_level = item.find("tech_level")

		if value is None or tech_level is None:
			continue
		else:
			yield (item, value, tech_level)

# breaks e.g. `4d6+2 [5d] (3) cr ex` into individual values
damage_parse = re.compile(r"""
	(?:
		([0-9]+)?\s*			# full dice multiplier (e.g. x in xd+5)
		d\s*					# the 'd' between the multiplier and the modifier

		([\+-]\s*				# start of the modifier sub-expression (e.g. x in 5d+x). Also, +/-
			[0-9]+				# the modifier
		)?\s*					# end of the modifier sub-expression
	)?

	(?:\[					# fragmentation damage can also have modifiers :'|

		(?:
			([0-9]+)?\s*		# full dice multiplier (e.g. x in xd+5)
			d\s*				# the 'd' between the multiplier and the modifier
			([\+-]\s*			# start of the modifier sub-expression (e.g. x in 5d+x). Also, +/-
				[0-9]+			# the modifier
			)?\s*				# end of the modifier sub-expression
		)?

	\])?\s*					# done fragmentation damage

	(?:						# start of the dr divisor sub-expression (e.g. x in 5d+3 (x))
		\(([0-9\.]+)\)		# dr divisor e.g. (##)
	)?\s*

	(aff|burn|burn\s*ex|cor|cr|cr\s*ex|cut|fat|imp|pi-|pi|pi\+|pi\+\+|spec\.|Spec\.|tox)?\s* # damage type
	""", re.VERBOSE) # TODO: shotguns

# gets all specializations and returns a tuple of (name, specialization, default modifier)
def get_specializations(firearm_elem):
	defaults = firearm_elem.findall(".//default")
	for default in defaults:
		specialization = default.find("specialization")
		modifier = default.find("modifier")
		name = default.find("name")
		if specialization is None or modifier is None or name is None:
			continue
		else:
			yield (name.text, specialization.text, int(modifier.text))

def is_shotgun(firearm_elem):
	return ("Guns", "Shotgun", 0) in get_specializations(firearm_elem)

def is_law(firearm_elem):
	return ("Guns", "LAW", 0) in get_specializations(firearm_elem)

def is_grenade_launcher(firearm_elem):
	return ("Guns", "Grenade Launcher", 0) in get_specializations(firearm_elem)

def is_gun(firearm_elem):
	for (name, _, _) in get_specializations(firearm_elem):
		if name == "Guns":
			return True
	return False

# formats damage values nicely for the character builder
def format_damage(full_dice, modifier, frag_full_dice, frag_modifier, armour_divisor, damage_type):
	output = ""
	if full_dice is not None:
		output += "{}d".format(full_dice)

		if modifier is not None:
			if modifier < 0:
				output += "{} ".format(modifier)
			elif modifier > 0:
				output += "+{} ".format(modifier)
			else:
				output += " "

	if frag_full_dice is not None:
		output += "[{}d".format(frag_full_dice)

		if frag_modifier is not None:
			if frag_modifier < 0:
				output += "{}".format(frag_modifier)
			elif frag_modifier > 0:
				output += "+{}".format(frag_modifier)

		output += "] "

	if armour_divisor is not None and not armour_divisor == 0 and not armour_divisor == 1:
		output += "({}) ".format(armour_divisor)

	if damage_type is not None:
		output += damage_type

	return output.strip()

for (item_elem, value_elem, tech_level_elem) in get_valued(all_equipment):
	try:
		# Calculate price multiplier
		tech_level = Fraction(tech_level_elem.text)
		price_multiplier = 0
		if 0 <= tech_level and tech_level <= 4:
			price_multiplier = 1
		else:
			price_multiplier = 2**(tech_level-4)

		# Calculate new price
		value = Fraction(value_elem.text)
		new_value = value * price_multiplier

		value_elem.text = str(new_value)
	except ValueError as e:
		print("Encountered error updating price of {}.".format(item_elem.find("description").text))

for (firearm_elem, damage_elem, value_elem, tech_level_elem) in get_firearms(all_equipment):
	# Filter out shotguns
	if not is_gun(firearm_elem) or is_shotgun(firearm_elem) or is_law(firearm_elem) or is_grenade_launcher(firearm_elem):
		continue

	(full_dice, modifier, frag_full_dice, frag_modifier, armour_divisor, damage_type) = damage_parse.match(damage_elem.text).groups()

	if frag_full_dice is not None or frag_modifier is not None:
		continue

	if full_dice is not None:
		if modifier is None:
			modifier = 0
		new_average = (max((Fraction(full_dice)*Fraction("3.5") + Fraction(modifier)), 0)/Fraction("7"))
		new_average_fraction = abs(new_average - floor(new_average))
		new_full_dice = floor(new_average)

		new_modifier = 0
		if new_average_fraction <= (Fraction("1/3")):
			new_modifier = 1
		elif new_average_fraction <= (Fraction("2/3")):
			new_modifier = 2
		else:
			new_modifier = -1
			new_full_dice += 1

		if new_full_dice == 0:
			new_full_dice = 1
			if new_modifier == 1:
				new_modifier = -3
			elif new_modifier == 2:
				new_modifier = -2
			else:
				raise Exception()

		new_armour_divisor = 2
		if armour_divisor is not None:
			new_armour_divisor = Fraction(armour_divisor)*2
		
		damage_elem.text = format_damage(new_full_dice, new_modifier, frag_full_dice, frag_modifier, new_armour_divisor, damage_type)

with open(output_filename, "wb") as output_file:
	tree.write(output_file)