On Wed, Nov 30, 2011 at 2:54 PM, <josef.pktd@gmail.com> wrote:
On Wed, Nov 30, 2011 at 3:45 PM, <josef.pktd@gmail.com> wrote:
On Wed, Nov 30, 2011 at 3:25 PM, Alacast <alacast@gmail.com> wrote:
axis=0 (the default) works fine. axis=1, etc, is clearly wrong. Am I misunderstanding how to use this, or is this a bug?
In [16]: i = rand(4,4)
In [17]: i Out[17]: array([[ 0.85367762, 0.25348857, 0.23572615, 0.50403358], [ 0.70199066, 0.81872151, 0.47357357, 0.20425537], [ 0.31042673, 0.25837984, 0.73550134, 0.57970176], [ 0.42828877, 0.60988596, 0.04059321, 0.73944219]])
In [18]: zscore(i, axis=0) Out[18]: array([[ 1.30128758, -0.96195723, -0.52119142, -0.01453907], [ 0.59653471, 1.38544585, 0.39284654, -1.55756529], [-1.22271057, -0.94164388, 1.39942427, 0.37494213], [-0.67511172, 0.51815526, -1.27107939, 1.19716222]])
In [19]: zscore(i[:,0]) Out[19]: array([ 1.30128758, 0.59653471, -1.22271057, -0.67511172])
In [20]: zscore(i[:,0])==zscore(i,axis=0)[:,0] Out[20]: array([ True, True, True, True], dtype=bool)
In [21]: zscore(i, axis=1) Out[21]: array([[-0.99378502, -1.59397407, -1.61173649, -1.34342906], [-1.6379836 , -1.52125275, -1.86640069, -2.13571889], [-2.09968257, -2.15172946, -1.67460796, -1.83040754], [-1.29796925, -1.11637205, -1.68566481, -0.98681582]]) #The above is obviously wrong, as everything has a negative z score
In [22]: zscore(i[0,:]) Out[22]: array([ 1.56824016, -0.83321371, -0.90428403, 0.16925757])
In [23]: zscore(i[0,:])==zscore(i,axis=1)[0,:] Out[23]: array([False, False, False, False], dtype=bool) #Using axis=1 produces different results from taking a row directly.
In [24]: zscore(i, axis=-1) Out[24]: array([[-0.99378502, -1.59397407, -1.61173649, -1.34342906], [-1.6379836 , -1.52125275, -1.86640069, -2.13571889], [-2.09968257, -2.15172946, -1.67460796, -1.83040754], [-1.29796925, -1.11637205, -1.68566481, -0.98681582]]) #Getting rows by using axis=-1 is no better (this is the same result as axis=1
This looks like a serious bug to me. I don't know what happened here (.
The docstring example also has negative numbers only.
???
I'm looking into it
Thanks for reporting
a misplaced axis: if axis>0 then it calculates x - mean/std instead of (x - mean) / std
now, how did this go through the testing ?
There is only one test for zscore, on a 1-d sample without the axis keyword. Warren
Josef
Josef
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