[Baypiggies] Raw file input and python

Glen Jarvis glen at glenjarvis.com
Sat Feb 12 20:48:56 CET 2011


Yes, of course!  That's what I'm thinking of..  If I were "thinking in C"
that would have come to me quicker... Oh well..

Thanks for that!  :)


Glen


On Sat, Feb 12, 2011 at 11:28 AM, Michael Pittaro <
mikeyp at lahondaresearch.org> wrote:

>
> On Sat, Feb 12, 2011 at 11:20 AM, Glen Jarvis <glen at glenjarvis.com> wrote:
>
>> Oh, and I'm constrained to Python 2.5 or lower only :(
>>
>> Glen
>>
>> On Sat, Feb 12, 2011 at 11:19 AM, Glen Jarvis <glen at glenjarvis.com>wrote:
>>
>>> I remember, about three years ago, reading someone's answer to a question
>>> very similar to this. But, I can't find it now.
>>>
>>> I have a raw input file where the first "entity" is a 64-bit unsigned
>>> integer and the remaining items in the file are 32-bit unsigned integers
>>> (until the end of the file).
>>>
>>> I vaguely remember there was already a module to cleanly handle this. I
>>> could, of course, open the file (f) in binary mode and do an f.read() on
>>> each byte and figure thing out. But, one will have to think of byte
>>> swapping, variable "sizes", etc. when running on different systems.
>>>
>>> I thought there was a layer above this that would take care of the
>>> mapping of data in the file (i.e., a raw dump/raw read) to a set of
>>> variables, taking care of byte swapping if needed, size of types, etc. as
>>> long as I specified the format (i.e., first should be 64-bit unsigned,
>>> second... etc.)
>>>
>>> Am I mistaking that this exists (i.e., did I just make this up)?
>>>
>>> Cheers,
>>>
>>>
>>>
> You probably are thinking of struct  - perfect for byte level unpacking of
> records.
>
> http://www.doughellmann.com/PyMOTW/struct/
>
>
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