On Mon, Aug 10, 2009 at 11:55 AM, Keith Goodman<kwgood...@gmail.com> wrote: > On Thu, Aug 6, 2009 at 9:07 AM, Robert Kern<robert.k...@gmail.com> wrote: >> On Thu, Aug 6, 2009 at 11:03, Keith Goodman<kwgood...@gmail.com> wrote: >>> On Thu, Aug 6, 2009 at 8:55 AM, <josef.p...@gmail.com> wrote: >>>> What's the best way of getting back the correct shape to be able to >>>> broadcast, mean, min,.. to the original array, that works for >>>> arbitrary dimension and axis? >>>> >>>> I thought I have seen some helper functions, but I don't find them anymore? >>>> >>>> Josef >>>> >>>>>>> a >>>> array([[1, 2, 3, 3, 0], >>>> [2, 2, 3, 2, 1]]) >>>>>>> a-a.max(0) >>>> array([[-1, 0, 0, 0, -1], >>>> [ 0, 0, 0, -1, 0]]) >>>>>>> a-a.max(1) >>>> Traceback (most recent call last): >>>> File "<pyshell#135>", line 1, in <module> >>>> a-a.max(1) >>>> ValueError: shape mismatch: objects cannot be broadcast to a single shape >>>>>>> a-a.max(1)[:,None] >>>> array([[-2, -1, 0, 0, -3], >>>> [-1, -1, 0, -1, -2]]) >>> >>> Would this do it? >>> >>>>> pylab.demean?? >>> Type: function >>> Base Class: <type 'function'> >>> String Form: <function demean at 0x3c5c050> >>> Namespace: Interactive >>> File: /usr/lib/python2.6/dist-packages/matplotlib/mlab.py >>> Definition: pylab.demean(x, axis=0) >>> Source: >>> def demean(x, axis=0): >>> "Return x minus its mean along the specified axis" >>> x = np.asarray(x) >>> if axis: >>> ind = [slice(None)] * axis >>> ind.append(np.newaxis) >>> return x - x.mean(axis)[ind] >>> return x - x.mean(axis) >> >> Ouch! That doesn't handle axis=-1. >> >> if axis != 0: >> ind = [slice(None)] * x.ndim >> ind[axis] = np.newaxis > > Ouch! That doesn't handle axis=None. > > if axis: > ind = [slice(None)] * x.ndim > ind[axis] = np.newaxis
that's why I used if axis != 0 and not axis is None: and included a testcase for None. (although my version looks a bit verbose but explicit) Josef > _______________________________________________ > 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
