[Numpy-discussion] performance issue (again)
Tue Apr 21 17:41:12 CDT 2009
On Tue, Apr 21, 2009 at 6:23 PM, Keith Goodman <firstname.lastname@example.org> wrote:
> On 4/21/09, Mathew Yeates <email@example.com> wrote:
> > Hi
> > I posted something about this earlier
> > Say I have 2 arrays X and Y with shapes (N,3) where N is large
> > I am doing the following
> > for row in range(N):
> > result=polyfit(X[row,:],Y[row,:],1,full=True) # fit 3 points with a
> > This takes forever and I was hoping to find a way to speed things up.
> > But now I'm starting to wonder if this pointless. If the routine "poly
> > fit takes a long time, when compared with the time for a Python
> > function call, then things can't be sped up.
> > Any comments?
> If you remove the mean from x and y (along axis = 1) then can't you
> just do something like
> (x*y).sum(1) / (x*x).sum(axis=1)
I think that's what I said 8 days ago.
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