[Numpy-discussion] Problems casting object arrays to string type on Ubuntu
Tue Nov 24 13:46:43 CST 2009
> I suspect you're running into this bug:
> This has been fixed in SVN r7514, (and thus 1.4 pre releases), so it's
> not a platform difference.
Great, thanks for the reply!
> > <mailto:firstname.lastname@example.org>> wrote:
> > Hi all,
> > I'm having some issues casting object arrays to string type,
> > especially on my Ubuntu installation. (Ubuntu Jaunty, 9.04, with
> > Numpy v. 1.3.)
> > With small arrays, the conversion is just wrong. With large
> > arrays, there seems to be some memory corruption. Conversion to
> > int or float (when appropriate) seems to work.
> > For instance, here are some examples of errors with small arrays:
> > >>> X = numpy.array([13,14],'object')
> > >>> X.astype('|S2')
> > array(['13', '\xb2'],
> > dtype='|S2')
> > >>> X.astype('int') #conversion to int or float seems to
> > work fine
> > array([13, 14])
> > >>> X.astype(float)
> > array([ 13., 14.])
> > >>> X = numpy.array(['cat','bat'],'object')
> > >>> X.astype('|S3')
> > array(['cat', '\x00ba'],
> > dtype='|S3')
> > Large arrays:
> > In : X = numpy.array(['cat','bat']*300000,'object')
> > In : Y = X.astype('|S3')
> > *** glibc detected *** /usr/bin/python: munmap_chunk(): invalid
> > pointer: 0xb7cd5008 ***
> > I do NOT have this problem with Numpy 1.4.0.dev7746, installed on
> > my OSX 10.5.8 machine. There, everything seems to work fine.
> > What's going on? I feel like I've seem some traffic about related
> > issues on the list before, but I couldn't quite tell from reading
> > the threads what the "final upshot" of the discussion was ...
> > Is this something that was fixed in recent NumPy 1.4 releases, or
> > is something about my Ubuntu vs. OSX installations? Generally
> > speaking can I / should I be relying on casting from object arrays
> > to do the "right" (or "intuitive") thing?
> > thanks,
> > Dan
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> Michael Droettboom
> Science Software Branch
> Operations and Engineering Division
> Space Telescope Science Institute
> Operated by AURA for NASA
> NumPy-Discussion mailing list
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