CODEWITHSUNDEEP
python
MRSK
MRSK

Reputation: 63

How to compare 2 files in Python while ignoring lines with comments (i.e line start with #)

I've got two files and its content looks like below

# version 17.3  
# Config info for 0092  
# Data for sgs  
# State : NA  
# Length : NA  
# Generated on Wed Apr 29 10:30:12 2015  
------------------------------------  
rest of the data  
------------------------------------

I want to compare the 2 files after ignoring the lines start with "#".
I tried file compare module, it does comparison at block level(reading the whole file as a block and comparing it). I wrote a simple code to do line by line comparison and it doesn't seem to work.

def extract_lines(files):   
for line in enumerate(files):  
    if line!= "#":  
        yield line  

with open(file1) as f1:  
with open(file2) as f2:  
    for (line1), (line2) in itertools.izip( extract_lines(f1), extract_lines(f2)):  
         if line1 != line2:  
             print "They are different"  
             break  
         else:  
            print "They are identical.

Upvotes: 1

Views: 1250

Answers (2)

Padraic Cunningham
Padraic Cunningham

Reputation: 180401

I presume you are comparing the lines in pairs due to zipping, you can zip them together using two generator expressions to filter lines starting with #:

from itertools import izip

with open("in1.txt") as f, open("in2.txt") as f2:
    a = (line for line in f if not line.startswith("#"))
    b = (line for line in f2 if not line.startswith("#"))
    for l1, l2 in zip(a ,b):
        print(l1,l2)

Upvotes: 2

DeepSpace
DeepSpace

Reputation: 81594

In extract_lines function, instead of 

for line in enumerate(files):
    if line!= "#":

you should do:

for line in files:
    if not line.startswith("#"):

Upvotes: 3

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