[Numpy-discussion] Adopt Mersenne Twister 64bit?

Neal Becker ndbecker2@gmail....
Thu Mar 14 06:00:39 CDT 2013


Robert Kern wrote:

> On Wed, Mar 13, 2013 at 12:16 AM, Neal Becker <ndbecker2@gmail.com> wrote:
>> I guess I talked to you about 100 years ago about sharing state between numpy
>> rng and code I have in c++ that wraps boost::random.  So is there a C-api for
>> this RandomState object I could use to call from c++?  Maybe I could do
>> something with that.
> 
> There is not one currently. Cython has provisions for sharing such
> low-level access to other Cython extensions, but I'm not sure how well
> it works for exporting data pointers and function pointers to general
> C/++ code. We could probably package the necessities into a struct and
> export a pointer to it via a PyCapsule.
> 

One thing this code doesn't do: it requires construction of the wrapper class 
passing in a RandomState object.  It doesn't verify you actually gave it a 
RandomState object.  It's hard to do that.  The problem as I see it is to 
perform this check, I need the RandomStateType object, which unfortunately 
mtrand.so does not export.

The only way to do it is in c++ code:

1. import numpy.random
2. get RandomState class
3. call it to create RandomState instance
4. get the ob_type pointer.

Pretty ugly:

  object mod = object (handle<> 
(borrowed((PyImport_ImportModule("numpy.random")))));
  object rs_obj = mod.attr("RandomState");
  object rs_inst = call<object> (rs_obj.ptr(), 0);
  RandomStateTypeObj = rs_inst.ptr()->ob_type;




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