Take part of a regex search result in Python -

Take part of a regex search result in Python -

i want read in header file , output each of variables has form x = 1.0; double = x;

at moment i've got this, outputs whole line:

import re input = open("file_with_vars.hpp", 'r') out = open("output.txt", 'w') line in input: if re.match("(.*) = (\d)", line): print >> out, line

but can't work out how take part of line , output variable name , double string file.

edit: have

for line in cell: m = re.search('(.*)\s*=\s*(\d+\.\d+)', line) print m.group()

but error ' attributeerror: 'nonetype' object has no attribute 'group' '

use search instead of match

the regex .*\s*=\s*\d+\.\d+

test:

import re y="x=1.0" m=re.search('(.*)\s*=\s*(\d+\.\d+)',y)

the group function can used extract matched strings as

>>> print m.group() 'x=1.0' >>> print m.group(1)` 'x' >>> print m.group(2) '1.0'

edit

how search lines within file

for line in cell: try: m = re.search('(.*)\s*=\s*(\d+\.\d+)', line) print m.group() except attributeerror: pass

the nonetype error caused because lines in file doesnot match regex returning none search method.

the try except takes care of exception.

pass null statement in python

for input file

x=10.2 y=15.3 z=12.4 w=48

creates output as

x=10.2 y=15.3 z=12.4

see here w=48 doesnt match regex returning nonetype, safely handled try block

or

as jerry pointed out, if can create more simple

for line in cell: m = re.search('\s*\s*=\s*(\d+\.\d+)', line) if m: print m.group()

python regex