Devanagari to Arabic numerals

d2r.py

import re

f = open('surasundari.xml','r')
w = open('surasundari-lg.xml','w')
num = re.compile(r'"([०१२३४५६७८९]+)"')
d2r_num = {'०':'0', '१':'1', '२':'2', '३':'3', '४':'4', '५':'5', '६':'6', '७':'7','८':'8','९':'9'}
text = f.readlines()
def num_d2r(number):
    rString = ''
    for s in str(number):
        rString += d2r_num[s]
    return str(rString)
for i in range(len(text)):
    match = num.search(text[i])
    if (match):
        result = re.sub(match.group(1),num_d2r(match.group(1)),text[i])
    else:
        result = text[i]
    w.write(result)