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:] On Jan 23, 2012, at 12:55 PM, David Warde-Farley wrote: > I've reproduced this (rather serious) bug myself and confirmed that it exists > in master, and as far back as 1.4.1. > > I'd really appreciate if someone could reproduce and confirm on another > machine, as so far all my testing has been on our single high-memory machine. > > Thanks, > David > > On Mon, Jan 23, 2012 at 05:23:28AM -0500, David Warde-Farley wrote: >> A colleague has run into this weird behaviour with NumPy 1.6.1, EPD 7.1-2, >> on Linux (Fedora Core 14) 64-bit: >> >>> a = numpy.array(numpy.random.randint(256,size=(5000000,972)),dtype='uint8') >>> b = numpy.random.randint(5000000,size=(4993210,)) >>> c = a[b] >> >> It seems c is not getting filled in full, namely: >> >>> In [14]: c[1000000:].sum() >>> Out[14]: 0 >> >> I haven't been able to reproduce this quite yet, I'll try to find a machine >> with sufficient memory tomorrow. But does anyone have any insight in the >> mean time? It smells like some kind of integer overflow bug. >> >> Thanks, >> >> David >> _______________________________________________ >> NumPy-Discussion mailing list >> [email protected] >> http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ > NumPy-Discussion mailing list > [email protected] > http://mail.scipy.org/mailman/listinfo/numpy-discussion _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
