open file and format readin

fopen = open("filename.txt", "r");
a = [];
b = [];
str = fopen.readline()
a.append(str.split(' ')[0]);
if len(str.split(' ')) > 2:
 b.append(str.split(' ')[2])
else:
 b.append(str.split(' ')[1])

while ( str != '' ):
 print str
 str = fopen.readline()
        if (str !=''):
  a.append(str.split(' ')[0])
  if len(str.split(' ')) > 2:
   b.append(str.split(' ')[2])
  else:
   b.append(str.split(' ')[1])