root/galaxy-central/eggs/GeneTrack-2.0.0_beta_1_dev_48da9e998f0caf01c5be731e926f4b0481f658f0-py2.6.egg/genetrack/roman.py @ 3

"""Convert to and from Roman numerals

This program is part of "Dive Into Python", a free Python book for
experienced programmers.  Visit http://diveintopython.org/ for the
latest version.
"""

__author__ = "Mark Pilgrim (mark@diveintopython.org)"
__version__ = "$Revision: 1.3 $"
__date__ = "$Date: 2004/05/05 21:57:19 $"
__copyright__ = "Copyright (c) 2001 Mark Pilgrim"
__license__ = "Python"

import re

#Define exceptions
class RomanError(Exception): pass
class OutOfRangeError(RomanError): pass
class NotIntegerError(RomanError): pass
class InvalidRomanNumeralError(RomanError): pass

#Define digit mapping
romanNumeralMap = (('M',  1000),
                                   ('CM', 900),
                                   ('D',  500),
                                   ('CD', 400),
                                   ('C',  100),
                                   ('XC', 90),
                                   ('L',  50),
                                   ('XL', 40),
                                   ('X',  10),
                                   ('IX', 9),
                                   ('V',  5),
                                   ('IV', 4),
                                   ('I',  1))

def toRoman(n):
        """convert integer to Roman numeral"""
        if not (0 < n < 5000):
                raise OutOfRangeError, "number out of range (must be 1..4999)"
        if int(n) <> n:
                raise NotIntegerError, "non-integers can not be converted"

        result = ""
        for numeral, integer in romanNumeralMap:
                while n >= integer:
                        result += numeral
                        n -= integer
        return result

#Define pattern to detect valid Roman numerals
romanNumeralPattern = re.compile('''
        ^                                  # beginning of string
        M{0,4}                    # thousands - 0 to 4 M's
        (CM|CD|D?C{0,3})        # hundreds - 900 (CM), 400 (CD), 0-300 (0 to 3 C's),
                                                #                       or 500-800 (D, followed by 0 to 3 C's)
        (XC|XL|L?X{0,3})        # tens - 90 (XC), 40 (XL), 0-30 (0 to 3 X's),
                                                #               or 50-80 (L, followed by 0 to 3 X's)
        (IX|IV|V?I{0,3})        # ones - 9 (IX), 4 (IV), 0-3 (0 to 3 I's),
                                                #               or 5-8 (V, followed by 0 to 3 I's)
        $                                  # end of string
        ''' ,re.VERBOSE)

def fromRoman(s):
        """convert Roman numeral to integer"""
        if not s:
                raise InvalidRomanNumeralError, 'Input can not be blank'
        if not romanNumeralPattern.search(s):
                raise InvalidRomanNumeralError, 'Invalid Roman numeral: %s' % s

        result = 0
        index = 0
        for numeral, integer in romanNumeralMap:
                while s[index:index+len(numeral)] == numeral:
                        result += integer
                        index += len(numeral)
        return result