#!/usr/bin/env python import getopt import sys from optparse import OptionParser name = 'bignum' version = '1.0' class BigNum(object): si_mapping = { None: "doesn't have a unit", 1: ((u'd', "deca"), (u'd', "deci")), 2: ((u'h', "hecto"), (u'c', "centi")), 3: ((u'k', "kilo"), (u'm', "milli")), 6: ((u'M', "Mega"), (u'\u00B5', "micro")), 9: ((u'G', "Giga"), (u'n', "nano")), 12: ((u'T', "Tera"), (u'p', "pico")), 15: ((u'P', "Peta"), (u'f', "femto")), 18: ((u'E', "Exa"), (u'a', "atto")), 21: ((u'Z', "Zetta"), (u'z', "zepto")), 24: ((u'Y', "Yotta"), (u'y', "yocto")), u'd': (('deca', 'deci'), (1, -1)), u'h': (('hecto',), (2)), u'c': (('centi',), (-2,)), u'k': (('kilo',), (3,)), u'm': (('milli',), (-3,)), u'M': (('Mega',), (6,)), u'\u00B5': (('micro',), (-6,)), u'G': (('Giga',), (9,)), u'n': (('nano',), (-9,)), u'T': (('Tera',), (12,)), u'p': (('pico',), (-12,)), u'P': (('Peta',), (15,)), u'f': (('femto',), (-15,)), u'E': (('Exa',), (18,)), u'a': (('atto',), (-18,)), u'Z': (('Zetta',), (21,)), u'z': (('zepto',), (-21,)), u'Y': (('Yotta',), (24,)), u'y': (('yocto',), (-24,)), u'deca': u'd', u'deci': u'd', u'hecto': u'h', u'centi': u'c', u'kilo': u'k', u'milli': u'm', u'Mega': u'M', u'micro': u'\u00B5', u'Giga': u'G', u'nano': u'n', u'Tera': u'T', u'pico': u'p', u'Peta': u'P', u'femto': u'f', u'Exa': u'E', u'atto': u'a', u'Zetta': u'Z', u'zepto': u'z', u'Yotta': u'Y', u'yocto': u'y', } def __init__(self, num=0, size=0, unit='', closest=False): self.num = num self.size = size self.unit = unit self.closest = closest def lookup(self, exp, sign='+'): if abs(int(exp)) == 0: return None #self.si_mapping[None] if sign == '-': return self.si_mapping[exp][1] return self.si_mapping[exp][0] def lookup_full(self, key, sign=None): try: key = int(key) except ValueError: pass if key not in self.si_mapping: raise ValueError, 'Unknown unit' if isinstance(key, int): exp = key out = [] if sign in ('+', '-'): abbr, name = self.lookup(key, sign) out.append((exp, abbr, name)) else: abbr, name = self.lookup(key, '+') out = [(exp, abbr, name)] abbr, name = self.lookup(key, '-') out.append((exp, abbr, name)) for exp, abbr, name in out: print "10^%i has the name '%s' and the symbol '%s'" % (exp, name, abbr) return elif issubclass(type(key), basestring): if len(key) == 1: abbr = key if key == 'd': if sign == '+': exp = self.si_mapping['d'][1][0] name = self.si_mapping['d'][0][0] elif sign == '-': exp = self.si_mapping['d'][1][1] name = self.si_mapping['d'][0][1] else: print """'d' is either the symbol for 'deca', \ 10^1, or the symbol for 'deci', 10^-1""" return else: exp = self.si_mapping[key][1][0] name = self.si_mapping[key][0][0] print "'%s' is the symbol for '%s', a number with %i digits" % (abbr, name, exp) return elif len(key) > 1: name = key if key == 'deca': exp = self.si_mapping['d'][1][0] elif key == 'deci': exp = self.si_mapping['d'][1][1] else: abbr = self.si_mapping[key] exp = self.si_mapping[abbr][1][0] print "'%s' has the symbol '%s' and is a number with %i digits" % (name, abbr, exp) return def bignum(self, num=0, size=1): num = num or self.num size = size or self.size snum = "%e" % num spec, exp = snum.split('e') sign, exp = exp[0], int(exp[1:]) _, rest = divmod(exp, 3) exp = exp - rest si = self.lookup(exp, sign) left, right = spec.split('.') if rest: left = left + right[:rest] right = right[rest:] if len(left) == 3 and self.closest: si = self.lookup(exp+3, sign) left = '0.'+left+right[:size] left = left.rstrip('0') size = 0 if size: pp = "%s.%s" % (left, right[:size]) else: pp = left return pp, si def pprint(self, num=0, size=1, unit='', p=True): num = num or self.num pp, si = self.bignum(num, size) outstring = "%s%s %s" % (pp, si[0], unit) if p: print outstring return outstring def usage(): print """%(name)s %(version)s Usage: %(name)s [options] Options: -h --help Show this help and exit -c --closest Round off to the nearest SI unit -s --sign= Number of significant digits -u --unit SI unit (m, kg, l...)s -v --version Print version and exit Examples: %(name)s 500000 -> 500k %(name)s -c 500000 -> 0.5M %(name)s -s 2 7870977786795764 -> 7.87P %(name)s -u kg 9999999999999999 -> 10Pkg """ % {'name': name, 'version': version} if __name__ == '__main__': op = OptionParser(version="%%prog %s" % version) op.add_option("-c", "--closest", action="store_true", dest="closest", default=False, help="round off to the nearest SI unit") op.add_option("-s", "--sign", type="int", dest="size", help="number of significant digits") op.add_option("-u", "--unit", dest="unit", help="SI unit (m, kg, l...)") op.add_option("-l", "--lookup", dest="lookup", help="lookup an SI-unit") try: opts, args = getopt.getopt(sys.argv[1:], "chvl:u:s:", ["closest", "help", "unit=", "sign=", "lookup="]) except getopt.GetoptError: print 'foo' usage() sys.exit(2) num = 3.1415 size = 0 unit = '' closest = False lookup = False for o, a in opts: if o in ('-h', '--help'): usage() sys.exit() if o in ('-v', '--version'): print name, version sys.exit() if o in ('-c', '--closest'): closest = True if o in ('-u', '--unit'): unit = a if o in ('-l', '--lookup'): lookup = a if o in ('-s', '--sign'): try: size = int(a) except ValueError: print "'%s' cannot be interpreted as an integer" % a if lookup: bn = BigNum() bn.lookup_full(lookup) sys.exit() if not args: usage() sys.exit(2) bn = BigNum(num, size, unit, closest) for num in args: try: num = long(num) except ValueError: try: num = float(num) except ValueError: print "'%s' cannot be interpreted as a number" % num sys.exit(255) print bn.pprint(num, size, unit, False)