[Tutor] Omitting lines matching a list of strings from a file

[Christian Witts]

galaxywatcher at gmail.com wrote:
>> But I would do this with a list comprehension or generator
>> expression (depending on your Python version):
>>
>>
>> lines = [line for line in infile if line[146:148] not in omit_states]
>> print '\n'.join(lines)
>
> That's very helpful. Thanks. One formatting detail: there is a blank 
> line after each line printed, how do I ged rid of the extra blank lines?
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lines = [line.strip() for line in infile if line[146:148] not in 
omit_states]
print '\n'.join(lines)

or alternatively

lines = [line for line in infile if line[146:148] not in omit_states]
print ''.join(lines)

Just remember that doing a list comprehension like that on a large file 
will drastically reduce the speed of your application as well as 
introduce memory bloat.

-- 
Kind Regards,
Christian Witts