Python将阿拉伯数字转换为罗马数字的方法

def numToRomanNum(Num):
 """digital will be converted into Roman numerals,Ex: numToRomanNum(3999)"""
 if Num < 1 or Num > 3999:
 print 'The Num must in 1-3999'
 else:
 NumDic = {
 '1':('I','IV','V','IX'),
 '2':('X','XL','L','XC'),
 '3':('C','CD','D','CM'),
 '4':('M')
 }
 items = sorted(NumDic.items())
 retstr = ''
 for item in items:
 str = ''
 (Num,modNum) = divmod(Num,10)
 if modNum != 0:
 if item[0] != '4':
 if modNum <= 3:
 while modNum > 0:
 str = str.join(['',item[1][0]])
 modNum -= 1
 elif modNum < 5:
 str = item[1][1]
 elif modNum == 5:
 str = item[1][2]
 elif modNum < 9:
 str = item[1][2]
 while modNum > 5:
 str = str.join(['',item[1][0]])
 modNum -= 1
 else:
 str = item[1][3]
 else:
 while modNum > 0:
 str = str.join(['',item[1][0]])
 modNum -= 1
 retstr = str.join(['',retstr])
 return retstr