fulvia/modules/resistor.py

#!/usr/bin/env python3
"""
Resistor color band codes.
"""
import re
import argparse

from module import commands, example

suffix = {"k": 1000, "m": 10000000}

sigfig = {"black": 0,
		"brown": 1,
		"red": 2,
		"orange": 3,
		"yellow": 4,
		"green": 5,
		"blue": 6,
		"violet": 7,
		"grey": 8,
		"white": 9}
sigfig_inverse = {val: key for key, val in sigfig.items()}

multiplier = {"black": 1,
		"brown": 10,
		"red": 100,
		"orange": 1000,
		"yellow": 10000,
		"green": 100000,
		"blue": 1000000,
		"violet": 10000000,
		"grey": 100000000,
		"white": 1000000000,
		"gold": 0.1,
		"silver": 0.01}
multiplier_inverse = {val: key for key, val in multiplier.items()}

tolerance = {"brown": "±1%",
			"red": "±2%",
			"green": "±0.5%",
			"blue": "±0.25%",
			"violet": "±0.1%",
			"grey": "±0.05%",
			"gold": "±5%",
			"silver": "±10%",
			"none": "±20%"}

temp_coeff = {"black": "250 ppm",
			"brown": "100 ppm",
			"red": "50 ppm",
			"orange": "15 ppm",
			"yellow": "25 ppm",
			"blue": "10 ppm",
			"violet": "5 ppm"}


@commands("resist")
@example(".resist 10k", "brown black orange gold")
def resist(bot, trigger):
	"""
	Displays the color band code of a resistor for the given resistance.
	"""
	if not trigger.group(2):
		return bot.say("Please specify a value")
	parser = argparse.ArgumentParser()
	parser.add_argument("value", nargs="+")
	parser.add_argument("-r", "--reverse", action="store_true")
	parser.add_argument("-n", "--num_bands", type=int, choices=[3,4,5,6], default=4)
	args = parser.parse_args(trigger.group(2).split())

	if args.reverse: # bands-to-value
		bot.say(bands_to_value(" ".join(args.value)))
	else: # value-to-band
		if len(args.value) > 1:
			return bot.say("Too many values.")

		value = args.value[0].lower()
		mul = 1
		if value[-1] in ["k", "m"]:
			mul = suffix[value[-1]]
			value = value[:-1]
		try:
			value = float(value) * mul
		except ValueError:
			return bot.say("Invalid input.")
		return bot.say(value_to_band(value, args.num_bands))


def value_to_band(value, num_bands=4):
	"""
	Converts a given resistance value to a color band code.
	"""
	if value < 1:
		return "Value too small. Maybe this will be fixed in the future."
	else:
		if num_bands > 4:
			value = float(format(value, ".3g"))
		else:
			value = float(format(value, ".2g"))
		value = re.sub("\.0$", "", str(value))
	bands = []
	mul = ""

	if "." in value:
		if value[-2] == ".":
			mul = 0.1
		elif value[-3] == ".":
			mul = 0.01
		else:
			return "Error with sigfigs."
		value = value.replace(".", "")

	val1 = int(value[0])
	val2 = int(value[1])
	bands.append(sigfig_inverse[val1])
	bands.append(sigfig_inverse[val2])

	if num_bands > 4:
		value = value.ljust(4,"0")
		val3 = int(value[2])
		bands.append(sigfig_inverse[val3])

	if not mul:
		mul = 10**(len(value) - len(value.rstrip("0")))
	bands.append(multiplier_inverse[mul])

	# TODO: better tolerance
	bands.append("gold")

	if num_bands == 3:
		return " ".join(bands)

	# TODO: better temp coeff
	if num_bands == 6:
		bands.append("red")

	return " ".join(bands)


def bands_to_value(bands):
	"""
	Converts the given color band code into a resistance value.
	"""
	bands = bands.lower().split()
	ret = []

	if len(bands) > 4:
		value = bands[:3]
		bands = bands[3:]
	else:
		value = bands[:2]
		bands = bands[2:]
	value = [sigfig[v] for v in value]

	prod = ""
	for x in value:
		prod += str(x)
	prod = float(prod) * multiplier[bands[0]]

	if len(bands) == 1:
		return " ".join([str(prod), tolerance["none"]])
	if len(bands) == 2:
		return " ".join([str(prod), tolerance[bands[1]]])
	if len(bands) == 3:
		return " ".join([str(prod), tolerance[bands[1]], temp_coeff[bands[2]]])