CODEWITHSUNDEEP
python-3.x
MathGirl
MathGirl

Reputation: 75

Deleting characters not working correctly

I have a tex file contains about 1000 line like this:

(1, '0109_S3.p9.m13')
['(n-k)/2']
(2, '0109_S3.p5.m8')
['\\sigma_{i}+\\sigma_{j}']

I want to delete the first 2 and the last 2 characters from the even lines and delete the first and last characters from the odd lines. this is my function:

def remove_chars(filename):
    with open(filename, 'r') as f0:
        with open('new1.tex', 'a') as f1:
            for num, line in enumerate(f0, 1):
                if num  % 2 == 0:  
                    f1.write(line[2:-2])
                else:
                    f1.write(line[1:-1])
                f1.write('\n')

the result should be like this:

1, '0109_S3.p9.m13'
(n-k)/2
2, '0109_S3.p5.m8'
\sigma_{i}+\sigma_{j}

but I get this:

1, '0109_S3.p9.m13')
(n-k)/2'
2, '0109_S3.p5.m8')
\\sigma_{i}+\\sigma_{j}'

so it is deleting the first characters right but not the last. I can not see where is the problem coming from! Could you help with this please?

Upvotes: 0

Views: 34

Answers (2)

Martijn Pieters
Martijn Pieters

Reputation: 1121724

Your file lines include a newline character at the end; you are removing that character. You probably just want to remove it only if it is there:

with open('new1.tex', 'a') as f1:
    for num, line in enumerate(f0, 1):
        line = line.rstrip('\n')
        if num  % 2 == 0:  
            f1.write(line[2:-2])
        else:
            f1.write(line[1:-1])
        f1.write('\n')

Upvotes: 2

buc
buc

Reputation: 6358

The lines may contain a line terminator character \n at the end. You should that that into account, too.

Upvotes: 0

Related Questions