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Date: Sun, 22 Jan 2012 19:58:06 +0000
Subject: Re: Splitting a file from specific column content
From: Arnaud Delobelle <arnodel@gmail.com>
To: python-list@python.org
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:19231

On 22 January 2012 16:09, MRAB <python@mrabarnett.plus.com> wrote:
> On 22/01/2012 15:39, Arnaud Delobelle wrote:
[...]
>> Or more succintly (but not tested):
>>
>>
>> sections =3D [
>> =C2=A0 =C2=A0 ("3", "section_1")
>> =C2=A0 =C2=A0 ("5", "section_2")
>> =C2=A0 =C2=A0 ("\xFF", "section_3")
>> ]
>>
>> with open(input_path) as input_file:
>> =C2=A0 =C2=A0 lines =3D iter(input_file)
>> =C2=A0 =C2=A0 for end, path in sections:
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 with open(path, "w") as output_file:
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 for line in lines:
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 if line>=3D end:
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 br=
eak
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 output_file.writ=
e(line)
>>
> Consider the condition "line >=3D end".
>
> If it's true, then control will break out of the inner loop and start
> the inner loop again, getting the next line.
>
> But what of the line which caused it to break out? It'll be lost.

Of course you're correct - my reply was too rushed.  Here's a
hopefully working version (but still untested :).

sections =3D [
    ("3", "section_1")
    ("5", "section_2")
    ("\xFF", "section_3")
]

with open(input_path) as input_file:
    line, lines =3D "", iter(input_file)
    for end, path in sections:
        with open(path, "w") as output_file:
            output_file.write(line)
            for line in lines:
                if line >=3D end:
                    break
                output_file.write(line)

--=20
Arnaud