On Mon, Jan 23, 2012 at 1:33 PM, Travis Oliphant <teoliph...@gmail.com>wrote:
> Can you determine where the problem is, precisely. In other words, can > you verify that c is not getting filled in correctly? > > You are no doubt going to get overflow in the summation as you have a > uint8 parameter. But, having that overflow be exactly '0' would be > surprising. > > Can you verify that a and b are getting created correctly? Also, 'c' > should be a 2-d array, can you verify that? Can you take the sum along the > -1 axis and the 0 axis separately: > > print a.shape > print b.shape > print c.shape > > c[1000000:].sum(axis=0) > d = c[1000000:].sum(axis=-1) > print d[:100] > print d[-100:] > I am getting the same results as David. It looks like c just "stopped filling in" partway through the array. I don't think there is any overflow issue, since the result of sum() is up-promoted to uint64 when I do that. Travis, here are the outputs at my end - I cut out many zeros for brevity: In [7]: print a.shape (5000000, 972) In [8]: print b.shape (4993210,) In [9]: print c.shape (4993210, 972) In [10]: c[1000000:].sum(axis=0) Out[10]: array([0, 0, 0, .... , 0]) In [11]: d = c[1000000:].sum(axis=-1) In [12]: print d[:100] [0 0 0 ... 0 0] In [13]: print d[-100:] [0 0 0 ... 0 0 0] I looked at sparse subsamples with matplotlib - specifically, imshow(a[::1000, :]) - and the a array looks correct (random values everywhere), but c is zero past a certain row number. In fact, it looks like it becomes zero at row 575419 - I think for all rows in c beyond row 574519, the values will be zero. For lower row numbers, I think they are correctly filled (at least, by the sparse view in matplotlib). In [15]: a[b[574519], 350:360] Out[15]: array([143, 155, 11, 30, 212, 149, 110, 164, 165, 120], dtype=uint8) In [16]: c[574519, 350:360] Out[16]: array([143, 155, 11, 30, 212, 149, 0, 0, 0, 0], dtype=uint8) I'm using EPD 7.1, numpy 1.6.1, Linux installation (I don't know the kernel details) HTH, Aronne
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