On Fri, May 25, 2012 at 11:17 AM, Chris Withers <ch...@simplistix.co.uk>wrote:
> Hi All, > > I have an array: > > arrrgh = numpy.zeros(100000000) > > A sparse collection of elements will have values greater than zero: > > arrrgh[9999] = 2 > arrrgh[3453453] =42 > > The *wrong* way to do this is: > > for i in xrange(len(arrrgh)): > if arrrgh[i] > 1: > print i > > What's the right way? > > Chris > > np.nonzero(arrrgh > 1) Note, it returns a list of lists, one for each dimension of the input array. Cheers! Ben Root
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