Reg expression in python

Question

for line in open(fname, 'r'): 
    if re.search('#', line):
        #print(line)
        pass
    elif re.search('# segment: retract', line):
        print(line)
        print('break here')
        break
    else:
        outfile.write(line)

The elif statement does not work, can anybody help me with a regexp that matches

"# segment: retract"

the code does not even enter the elif statement.

Thanks

havexz · Accepted Answer · 2013-01-12 14:57:30Z

3

I don't think this is regex is the prob. The condition needs to be reversed like

if re.search('# segment: retract', line):
    print(line)
    print('break here')
    break
elif re.search('#', line):
    #print(line)
    pass
else:
    outfile.write(line)

The problem is the first if condition catching all lines starting with # and else never happens.

answered Jan 12, 2013 at 14:57

havexz

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Comments

score 3 · Accepted Answer · 2013-01-12 15:01:43Z

3

The first expression of the if clause will always match for lines containing '#'. So your more specific condition in the elif clause will never match since the more generic condition in the if clause is always executed. So you would test the more specific conditions first and move the more generic condition(s) into the elif part.

for line in open(fname, 'r'): 

    if re.search('# segment: retract', line):
        print(line)
        print('break here')
        break
    elif re.search('#', line):
        #print(line)
        pass
    else:
        outfile.write(line)

edited Jan 12, 2013 at 15:01

answered Jan 12, 2013 at 14:56

user2665694

1 Comment

Tim Pietzcker Over a year ago

No need for regex at all. if '# segment: retract' in line: is enough.

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