On Fri, May 25, 2012 at 11:17 AM, Chris Withers 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

for me, np.nonzero() and np.where() both work. It seems they have same function. chao 2012/5/27 Chris Withers

On 25/05/2012 16:21, Benjamin Root wrote:

...

np.nonzero(arrrgh > 1)

Did you mean np.where(arrrgh > 1)?for I didn't know you could use np.nonzero in the way your describe?

Chris

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