> > Well, if you do f = a[n, :], you would get a view, another object that > shares the data in memory with a but is a separate object.
OK, so it is a new object, with the properties of the slice it references, but if I write anything to it, it will consistently go back to the same spot in the original array. In general, if I work on that, and don't do something that allocates a new set of memory locations for that, it will reference the same memory location. If I do: a = np.zeros((20,30)) b = a[2,:] b += 1 # will add 1 to the original slice b.resize will fail... b = np.zeros((1,30)) # allocates new memory and disconnects the view The appropriate way to zero out the original memory locations would be to do something like b *= 0? Is there any way to force a writeback to the original view so long as the dimensions of what is being assigned to b is the same as the original? Or, is there a way to, say, enable a warking if I'm dropping a view? > Sorry I didn't get back to you earlier on this -- I was a bit busy > yesterday. It looks like weave.blitz isn't working on your second > line because you're not explicitly putting slices in some of the > dimensions, In numpy v[0:2] works for 1,2,3,4,.... dimensions, but > for a 2d array in blitz you have to use v[0:2,:], 3d v[0:2,:,:]. It's > a bit more picky. I think that's the problem with your second line > -- try replacing v[:] with v[0,:] and theta[1-curidx] with > theta[1-curidx, :]. (I may have missed some others.) OK, that seems to do it. I still actually get better performance (subsequent runs after compilation) with the straight numpy code. Strangely, I'm also getting that the flip/flop method is running a bit slower than having the separate prev_ variables. aff_input is rather large (~2000x14000), but the state vectors are only 14000 (or that x2 w/ flipflopping for some), each. Is there slowdown maybe because it is doing those 3 lines of blitz operations then doing a bunch of python numpy? Either way, It seems like I've got pretty good performance as well as a handle on using weave.blitz in the future. -jsnyder -- James Snyder Biomedical Engineering Northwestern University [EMAIL PROTECTED] PGP: http://fanplastic.org/key.txt _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
