[Numpy-discussion] Reading from binary file with memmap, with offset

Andreas Hilboll lists at hilboll.de
Thu Oct 10 09:17:26 EDT 2013


On 10.10.2013 15:07, Joe Kington wrote:
> You just need to supply the "offset" kwarg to "memmap".
> 
> for example:
> 
> with open(localfile, "r") as fd:
>   # read offset from first line of file
>   offset = int(next(fd).split()[-2])
>   np.memmap(fd, dtype="float32", mode="r", offset=offset)
> 
> Also, there's no need to do things like "offset =
> int(fd.readlines()[0].split()[-2])"
> 
> Just do "offset = int(next(fd).split()[-2])" instead.  Readlines reads
> the entire file into memory. You only want the first line.

Thanks, Joe, I actually didn't know `next` yet ...

-- Andreas.



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