On Thursday, January 19, 2012, Ruby Stevenson <ruby...@gmail.com> wrote: > hi, all > > I am a newbie on numpy ... I am trying to figure out, given an array, > how to get back position value based on some conditions. > Say, array([1, 0, 0, 0 1], and I want to get a list of indices where > it is none-zero, [ 0 , 4 ] > > The closest thing I can find from the doc is select(), but I can't > figure out how to use it properly. > > Thanks for your help. > > Ruby >
np.nonzero() Note that you typically use it with a Boolean array result like "a >= 4". Also note that it returns a tuple of index lists, on for each dimension. This can the be feed back into the array to get the values as a flat array. Ben Root
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