Does this help you:
Suppose (for a toy example) I have defined a Python function like this:
sage: def f(M):
....: d = M.det()
....: return d
And I have a file called testin.sage containing a large number of
lines like this:
[[1,2],[3,4]]
[[5,6],[7,8]]
[[1,2],[3,4]]
[[5,6],[7,8]]
[[1,2],[3,4]]
[[5,6],[7,8]]
Then from the command line I can do this:
sage: for l in open("/home/masgaj/testin.sage"):
print(f(Matrix(eval(l))))
and what I see is this:
-2
-2
-2
-2
-2
-2
As far as I know Python only reads the lines in the file one at at
time, and returns each as a string (hence the eval()), which you can
do what you like with.
I did something similar when I wanted to process a million elliptic
curves without reading them all in at once.
John
2008/11/2 Daniel Allcock <[EMAIL PROTECTED]>:
>
> Hi all, just got started with SAGE and I hope someone has a suggestion
> for me. I have a .sage file defining a big list of approx 170,000 4x4
> matrices with rational number entries, which I will want SAGE to do
> various things to. It takes SAGE 4-5 minutes to read in the file
> (which was produced by a C++ program), and surely this can be
> improved.
>
> I assumed that loading it into memory and then writing it to a .sobj
> file would give me something more manageable. But I get memory
> allocation errors:
>
> python(2102) malloc: *** vm_allocate(size=8421376) failed (error
> code=3)
> python(2102) malloc: *** error: can't allocate region
> python(2102) malloc: *** set a breakpoint in szone_error to debug
>
> Presumably the system has just run out of memory. This surprises me
> since the .sage file is only 12MB, and the .py file it creates is
> 37MB. The matrix entries are all small, numerators <10,000 and
> denominators < 200 or so. I'm working on a MacBook Pro with 2GB RAM,
> and the machine didn't have any other substantial load.
>
> I will need only one matrix at a time, so there should be no need to
> load in all of them at once. But poking around in SAGE and python
> docs hasn't shown me any simple way to, say, read in and execute a
> single line from some file.
>
> Thanks for your help,
> Daniel
>
> >
>
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