python - Unit conversion from mm to m in text file with text and numbers -

i'm trying convert following style text file mm m (i.e., divide numbers 1000). it's made of regular pattern , contains text numbers.

i have managed solve (eventually) using python, it's bit rough , ready completes task. suggestions/improvements appreciated.

import re import numpy np import linecache io import stringio  myfile = "file" results = open("results.txt","w")  in range(1,50000):     line = linecache.getline(myfile,i)     if re.search('[a-za-z]', line):         results.write(line)         elif line.isspace():         results.write(str(line))     elif re.search('[-]', line):         results.write(str(line))     else:         c = stringio(line)         data = np.loadtxt(c)         = np.array(data)         c = / 1000         d = str(c).replace('[','').replace(']','')         results.write(str(d)+'\n') results.close() 

the file so:

add tube 3033303.0 2998206.95111 106180.1625 60.325 6222.60621 y 0.0 0.0 0.0 add cube 3027189.24332 3032175.78955 114508.75 168.9 6170.76909 y 0.0 0.0 0.0 

desired outcome be;

add tube 3033.3030 2998.20695111 106.1801625 0.060325 6.22260621 y 0.0 0.0 0.0 add cube 3027.18924332 3032.17578955 114.50875 0.1689 6.17076909 y 0.0 0.0 0.0 

easy in perl

perl -pe 's-(\d+.?\d*)-($1/1000)-ge' file  add tube 3033.303 2998.20695111 106.1801625 0.060325 6.22260621 y 0 0 0 add cube 3027.18924332 3032.17578955 114.50875 0.1689 6.17076909 y 0 0 0