Splitting a file from specific column content

[Arnaud Delobelle]

On 22 January 2012 16:09, MRAB <python at mrabarnett.plus.com> wrote:
> On 22/01/2012 15:39, Arnaud Delobelle wrote:
[...]
>> Or more succintly (but not tested):
>>
>>
>> sections = [
>>     ("3", "section_1")
>>     ("5", "section_2")
>>     ("\xFF", "section_3")
>> ]
>>
>> with open(input_path) as input_file:
>>     lines = iter(input_file)
>>     for end, path in sections:
>>         with open(path, "w") as output_file:
>>             for line in lines:
>>                 if line>= end:
>>                     break
>>                 output_file.write(line)
>>
> Consider the condition "line >= 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 = [
    ("3", "section_1")
    ("5", "section_2")
    ("\xFF", "section_3")
]

with open(input_path) as input_file:
    line, lines = "", 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 >= end:
                    break
                output_file.write(line)

-- 
Arnaud