#Roman Numeral Converter
#Written By Brandon Martin
#Digital Sol
class IllegalCharacterError(Exception):
pass
def romanToNumber(numerals):
'''Converts a string of Roman Numerals (I,V,X,L,C,D,M) into an integer.'''
romanConversionTable = {
'I' : 1,
'V' : 5,
'X' : 10,
'L' : 50,
'C' : 100,
'D' : 500,
'M' : 1000
}
### Build List of Numbers ###
numberList = []
for letter in numerals:
# Build List of Numbers
if letter in romanConversionTable:
numberList += [romanConversionTable[letter]]
else:
raise IllegalCharacterError('{} is not a Roman Numeral'.format(letter))
if len(numberList) == 1:
return numberList[0]
### Construct Final Total ###
previous = numberList[-1]
total = previous
for current in range(len(numberList)-2,-1, -1):
if numberList[current] < previous:
total -= numberList[current]
else:
total += numberList[current]
previous = numberList[current]
return total
def numberToRoman(integer):
'''Converts an integer into a string of Roman Numerals.'''
if type(integer) != int:
raise TypeError('Input must be an integer.')
numberConversionTable = {
1 : 'I',
5 : 'V',
10 : 'X',
50 : 'L',
100 : 'C',
500 : 'D',
1000 : 'M'
}
quads = ('I','X','C')
doubs = ('V','L','D')
foundNumeral = ''
found = 0
### Build List of Roman Numerals ###
numeralList = []
for value in [1000,500,100,50,10,5,1]:
while integer >= value:
integer -= value
numeralList += [numberConversionTable[value]]
if len(numeralList) == 1: #Return result if only one symbol
return numeralList.pop()
### Modify List to Proper Formatting ###
finalNumeralList = []
repeats = 0
for numeral in numeralList:
if len(finalNumeralList) == 0:
# ADD FIRST NUMBER
finalNumeralList += [numeral]
else:
if numeral != finalNumeralList[len(finalNumeralList)-1]:
# CURRENT NUMERAL IS DIFFERENT FROM THE LAST
if 3 > repeats > 0:
# ADD IN ALL REPEATS
for i in range(repeats):
finalNumeralList += [finalNumeralList[-1]]
repeats = 0
finalNumeralList += [numeral]
else:
# CURRENT NUMERAL IS THE SAME AS THE LAST
repeats += 1
if repeats == 3 and numeral != 'M':
# EXCHANGE THREE ONES NUMERALS FOR ONE FIVES NUMERAL
modifiedNumeral = doubs[quads.index(numeral)]
if modifiedNumeral == finalNumeralList[len(finalNumeralList)-2]:
# NUMERALS IN A THREE DIGIT RANGE ADD TO 9
finalNumeralList.pop(len(finalNumeralList)-2)
if numeral != 'C':
finalNumeralList += [quads[quads.index(numeral)+1]]
else:
finalNumeralList += ['M']
else:
finalNumeralList += [modifiedNumeral]
repeats = 0
elif numeral == 'M':
# AUTOMATICALLY ADD M
finalNumeralList += ['M']
repeats = 0
if repeats > 0:
# ADD IN ANY REMAINING REPEATS
for i in range(repeats):
finalNumeralList += [finalNumeralList[-1]]
finalString = ''.join(finalNumeralList)
return finalString
