On Wed, Aug 26, 2009 at 1:26 AM, Robert Kern<robert.k...@gmail.com> wrote: > On Tue, Aug 25, 2009 at 16:18, Giuseppe Aprea<giuseppe.ap...@gmail.com> wrote: >> Hi, I would like to do something like this >> >> a=array([[1,2,3,4],[5,6,7,8],[4,5,6,0]]) >> idxList=[] >> for i in range(0,a.shape[1]): >> if len(nonzero(a[:,i])[0])==1: #want to extract column indices >> of those columns which only have one non vanishing element >> idxList.append(i) >> >> I already used where on !D array but I don't know if there is some function >> or >> some kind of syntax which allow you to evaluate a condition for each >> column(row). > > column_mask = ((a != 0).sum(axis=1) == 1) > idxArray = np.nonzero(column_mask)[0] # if you must > > -- > Robert Kern > > "I have come to believe that the whole world is an enigma, a harmless > enigma that is made terrible by our own mad attempt to interpret it as > though it had an underlying truth." > -- Umberto Eco > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
That's interesting. Thanks a lot! In my case that becames: column_mask = ((a != 0).sum(axis=0) == 1) idxArray = np.nonzero(column_mask)[0] cheers g _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
