[Numpy-discussion] Quikest way to create a symetric (diagonal???) matrix ?
Alexandre Fayolle
alexandre.fayolle@logilab...
Wed Mar 26 09:22:06 CDT 2008
On Wed, Mar 26, 2008 at 09:48:02AM -0400, Pierre GM wrote:
> All,
> What's the quickest way to create a diagonal matrix ? I already have the
> elements above the main diagonal. Of course, I could use loops:
> >>>m=5
> >>>z = numpy.arange(m*m).reshape(m,m)
> >>>for k in range(m):
> >>> for j in range(k+1,m):
> >>> z[j,k] = z[k,j]
> But I was looking for something more efficient.
From your code, you certainly meant "symetric" and not diagonal.
Maybe you can speed up things a bit by assigning slices:
>>> for k in range(m):
... z[k:, k] = z[k, k:]
--
Alexandre Fayolle LOGILAB, Paris (France)
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