Ole Streicher wrote:
Hi John
John Machin <sjmac...@lexicon.net> writes:
On Apr 25, 1:14 am, Ole Streicher <ole-usenet-s...@gmx.net> wrote:
John Machin <sjmac...@lexicon.net> writes:
From my access pattern, it would be probably better to combine 25 rows
into one slice and have one matrix where every cell contains 25 rows.
Are there any objections about that?
Can't object, because I'm not sure what you mean ... how many elements
in a "cell"?
Well, a matrix consists of "cells"? A 10x10 matrix has 100 "cells".
Yes yes but you said "every cell contains 25 rows" ... what's in a
cell? 25 rows, with each row containing what?
I mean: original cells.
I have 100.000x4096 entries:
(0,0) (0,1) ... (0,4095)
(1,0) (1,1) ... (1,4095)
...
(100.000,0) (100.000,1) ... (100.000,4095)
Choose a block size, and place the block in your output. For example,
using 128K byte blocks (and assuming each cell holds a single 8-byte
number), we could decide each block was a 128 x 128 sub-matrix of your
original. Then to get to a particular block, seek to its base address,
and use:
src = open('data.file', 'rb') # or wb or...
src.seek(block_number * 128 * 128 * 8)
block = numpy.fromfile(src, count=128 * 128)
block.shape = (128, 128)
and then you've got your sub-block.
--Scott David Daniels
scott.dani...@acm.org
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