Thanks a lot for the replies. I have misunderstood the output. When it says (array[0]), i thought it did not find anything as opposed to the zeroth row. (Still getting used to matlab indexing i guess !! ) .. Sorry !!
Thanks a lot for the sugestions though, Would keep it in mind .. From: santhu kumar <mesan...@gmail.com> > Subject: [Numpy-discussion] Nonzero behaving strangely? > To: numpy-discussion@scipy.org > Message-ID: > <aanlktinnfb6cbrudb3guaqsmcoq0dkywqy77j9hmm...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hello all, > > I am new to Numpy. I used to program before in matlab and am getting used > to > Numpy. > > I have a array like: > res > array([[ 33.35053669, 49.4615004 , 44.27631299, 1. , 2. > ], > [ 32.84263059, 50.24752036, 43.92291659, 1. , 0. > ], > [ 33.68999668, 48.90554673, 43.51746687, 1. , 0. > ], > [ 34.11564931, 49.77487763, 44.83843076, 1. , 0. > ], > [ 32.4641859 , 48.65469145, 45.09300791, 1. , 3. > ], > [ 32.15428526, 49.26922262, 45.92959026, 1. , 0. > ], > [ 31.23860825, 48.21824628, 44.30816331, 1. , 0. > ], > [ 30.71171138, 47.45600573, 44.9282456 , 1. , 0. > ], > [ 30.53843426, 49.07713258, 44.20899822, 1. , 0. > ], > [ 31.54722284, 47.61953925, 42.95235178, 1. , 0. > ], > [ 32.44334635, 48.10500653, 42.51103537, 1. , 0. > ], > [ 31.77269609, 46.53603145, 43.06468455, 1. , 0. > ], > [ 30.1820843 , 47.80819604, 41.77667819, 1. , 0. > ], > [ 30.78652668, 46.82907769, 40.38586451, 1. , 0. > ], > [ 30.05963091, 46.84268609, 39.54583693, 1. , 0. > ], > [ 31.75239177, 47.22768463, 40.00717713, 1. , 0. > ], > [ 30.94617127, 45.76986265, 40.68226643, 1. , 0. > ], > [ 33.20069679, 47.42127403, 45.66738249, 1. , 0. > ], > [ 34.39608116, 47.25481126, 45.4438599 , 1. , 0. > ]]) > > The array is 19X5. > When I do: > nid = (res[:,4]==2).nonzero() > nid tuple turns out to be empty. But the very first row satisfies the > criteria. > > nid = (res[:,4]==3).nonzero(), works out and finds the 5th row. > > Am i doing something wrong? > I basically want to find the rows whose fifth coloumn(4th in numpy matrix > format) is 2. > > Any suggestions? > Thanks > Santhosh > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mail.scipy.org/pipermail/numpy-discussion/attachments/20110317/2f46f2c1/attachment-0001.html > > ------------------------------ > > Message: 2 > Date: Thu, 17 Mar 2011 23:19:42 +0100 > From: Matthieu Brucher <matthieu.bruc...@gmail.com> > Subject: Re: [Numpy-discussion] Nonzero behaving strangely? > To: Discussion of Numerical Python <numpy-discussion@scipy.org> > Message-ID: > <aanlktimeipz6cpamauy2f_0mpjwkwjdwe0oc4wm-l...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi, > > Did you try np.where(res[:,4]==2) ? > > Matthieu > > 2011/3/17 santhu kumar <mesan...@gmail.com> > > > Hello all, > > > > I am new to Numpy. I used to program before in matlab and am getting used > > to Numpy. > > > > I have a array like: > > res > > array([[ 33.35053669, 49.4615004 , 44.27631299, 1. , 2. > > ], > > [ 32.84263059, 50.24752036, 43.92291659, 1. , 0. > > ], > > [ 33.68999668, 48.90554673, 43.51746687, 1. , 0. > > ], > > [ 34.11564931, 49.77487763, 44.83843076, 1. , 0. > > ], > > [ 32.4641859 , 48.65469145, 45.09300791, 1. , 3. > > ], > > [ 32.15428526, 49.26922262, 45.92959026, 1. , 0. > > ], > > [ 31.23860825, 48.21824628, 44.30816331, 1. , 0. > > ], > > [ 30.71171138, 47.45600573, 44.9282456 , 1. , 0. > > ], > > [ 30.53843426, 49.07713258, 44.20899822, 1. , 0. > > ], > > [ 31.54722284, 47.61953925, 42.95235178, 1. , 0. > > ], > > [ 32.44334635, 48.10500653, 42.51103537, 1. , 0. > > ], > > [ 31.77269609, 46.53603145, 43.06468455, 1. , 0. > > ], > > [ 30.1820843 , 47.80819604, 41.77667819, 1. , 0. > > ], > > [ 30.78652668, 46.82907769, 40.38586451, 1. , 0. > > ], > > [ 30.05963091, 46.84268609, 39.54583693, 1. , 0. > > ], > > [ 31.75239177, 47.22768463, 40.00717713, 1. , 0. > > ], > > [ 30.94617127, 45.76986265, 40.68226643, 1. , 0. > > ], > > [ 33.20069679, 47.42127403, 45.66738249, 1. , 0. > > ], > > [ 34.39608116, 47.25481126, 45.4438599 , 1. , 0. > > ]]) > > > > The array is 19X5. > > When I do: > > nid = (res[:,4]==2).nonzero() > > nid tuple turns out to be empty. But the very first row satisfies the > > criteria. > > > > nid = (res[:,4]==3).nonzero(), works out and finds the 5th row. > > > > Am i doing something wrong? > > I basically want to find the rows whose fifth coloumn(4th in numpy matrix > > format) is 2. > > > > Any suggestions? > > Thanks > > Santhosh > > > > _______________________________________________ > > NumPy-Discussion mailing list > > NumPy-Discussion@scipy.org > > http://mail.scipy.org/mailman/listinfo/numpy-discussion > > > > > > > -- > Information System Engineer, Ph.D. > Blog: http://matt.eifelle.com > LinkedIn: http://www.linkedin.com/in/matthieubrucher > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mail.scipy.org/pipermail/numpy-discussion/attachments/20110317/3b48f06c/attachment-0001.html > > > > ------------------------------ > > Message: 4 > Date: Thu, 17 Mar 2011 17:27:19 -0500 > From: Warren Weckesser <warren.weckes...@enthought.com> > Subject: Re: [Numpy-discussion] Nonzero behaving strangely? > To: Discussion of Numerical Python <numpy-discussion@scipy.org> > Message-ID: > <AANLkTi=sheodtbnqe07gco1f4wyeqzoojtyi6n-qi...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > On Thu, Mar 17, 2011 at 5:17 PM, santhu kumar <mesan...@gmail.com> wrote: > > > Hello all, > > > > I am new to Numpy. I used to program before in matlab and am getting used > > to Numpy. > > > > I have a array like: > > res > > array([[ 33.35053669, 49.4615004 , 44.27631299, 1. , 2. > > ], > > [ 32.84263059, 50.24752036, 43.92291659, 1. , 0. > > ], > > [ 33.68999668, 48.90554673, 43.51746687, 1. , 0. > > ], > > [ 34.11564931, 49.77487763, 44.83843076, 1. , 0. > > ], > > [ 32.4641859 , 48.65469145, 45.09300791, 1. , 3. > > ], > > [ 32.15428526, 49.26922262, 45.92959026, 1. , 0. > > ], > > [ 31.23860825, 48.21824628, 44.30816331, 1. , 0. > > ], > > [ 30.71171138, 47.45600573, 44.9282456 , 1. , 0. > > ], > > [ 30.53843426, 49.07713258, 44.20899822, 1. , 0. > > ], > > [ 31.54722284, 47.61953925, 42.95235178, 1. , 0. > > ], > > [ 32.44334635, 48.10500653, 42.51103537, 1. , 0. > > ], > > [ 31.77269609, 46.53603145, 43.06468455, 1. , 0. > > ], > > [ 30.1820843 , 47.80819604, 41.77667819, 1. , 0. > > ], > > [ 30.78652668, 46.82907769, 40.38586451, 1. , 0. > > ], > > [ 30.05963091, 46.84268609, 39.54583693, 1. , 0. > > ], > > [ 31.75239177, 47.22768463, 40.00717713, 1. , 0. > > ], > > [ 30.94617127, 45.76986265, 40.68226643, 1. , 0. > > ], > > [ 33.20069679, 47.42127403, 45.66738249, 1. , 0. > > ], > > [ 34.39608116, 47.25481126, 45.4438599 , 1. , 0. > > ]]) > > > > The array is 19X5. > > When I do: > > nid = (res[:,4]==2).nonzero() > > nid tuple turns out to be empty. But the very first row satisfies the > > criteria. > > > > nid = (res[:,4]==3).nonzero(), works out and finds the 5th row. > > > > Am i doing something wrong? > > I basically want to find the rows whose fifth coloumn(4th in numpy matrix > > format) is 2. > > > > > > Are you sure the value of res[0,4] is *exactly* 2.0, and not something > like, > say, 2.0000000000000009? > > Warren > > > > Any suggestions? > > Thanks > > Santhosh > > > > _______________________________________________ > > NumPy-Discussion mailing list > > NumPy-Discussion@scipy.org > > http://mail.scipy.org/mailman/listinfo/numpy-discussion > > > > > > > > > ------------------------------ > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > > > End of NumPy-Discussion Digest, Vol 54, Issue 75 > ************************************************ > -- bye and take care santhu
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