How to use a contiguous memory location of n bytes in python

[chachi]

Hi,

I want to know how to instantiate a data structure which has n bytes
(given by me) and is internally stored in a contiguous fashion. I know
list is not implemented like this, so I am in a fix. There seems to be
a buffer object available, but haven't seen it being used anywhere.
Does anyone know how to use Buffer? Say I want to write some data onto
the buffer and then write the contents of the entire buffer to a file
(without making a new string, but lets first get the buffer issue out
of the way), how do I do it?



Thanks,
ssg

[bearophileHUGS@lycos.com]

Re: How to use a contiguous memory location of n bytes in python

chachi:

I want to know how to instantiate a data structure which has n bytes
(given by me) and is internally stored in a contiguous fashion.

array.array("B" , ...) may be fit for you. You can also use a numpy
array of bytes.

Bye,
bearophile

[Aaron Brady]

Re: How to use a contiguous memory location of n bytes in python

On Nov 13, 6:40 pm, bearophileH...@ lycos.com wrote:

chachi:
>

I want to know how to instantiate a data structure which has n bytes
(given by me) and is internally stored in a contiguous fashion.

>
array.array("B" , ...) may be fit for you. You can also use a numpy
array of bytes.
>
Bye,
bearophile

Also, there is the 'mmap' module.

[Nick Craig-Wood]

Re: How to use a contiguous memory location of n bytes in python

bearophileHUGS@ lycos.com <bearophileHUGS @lycos.comwrote :

chachi:

I want to know how to instantiate a data structure which has n bytes
(given by me) and is internally stored in a contiguous fashion.

>
array.array("B" , ...) may be fit for you. You can also use a numpy
array of bytes.

The mmap module is useful also for larger amounts (>4k say).
mmap's are individually free-able so they don't fragment your memory.

http://docs.python.org/library/mmap.html

Eg create a 1 GB anonymous mmap, access it and then delete it

>>from mmap import mmap
>>a = mmap(-1, 1000000000)
>>a[0]

'\x00'

>>a[0] = 'z'
>>a[999999999]

'\x00'

>>a[999999999]='q'
>>a[999999999]

'q'

>>del a

--
Nick Craig-Wood <nick@craig-wood.com-- http://www.craig-wood.com/nick