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) Formations Python, Zope, Plone, Debian: http://www.logilab.fr/formations Développement logiciel sur mesure: http://www.logilab.fr/services Informatique scientifique: http://www.logilab.fr/science
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