[Numpy-discussion] resize in old Numeric

Stefan van der Walt stefan@sun.ac...
Wed Dec 12 13:35:15 CST 2007


Hi Christiaan

On Wed, Dec 12, 2007 at 07:39:49PM +0100, Christian Meesters wrote:
> I need to flatten a simple 3x3 array and try to do that with resize.
> First time works, next time it doesn't. Here is an example:
> 
> In [1]: from Numeric import *
> 
> In [2]: a = array([[ 0.50622966, -0.54764389, -0.66619644],
> [ 0.44338279, -0.4973092, 0.7457228 ],[-0.73969131, -0.67288704,
> -0.00893311]])
> 
> In [3]: a.resize((9,))
> Out[3]: 
> array([ 0.50622966, -0.54764389, -0.66619644,  0.44338279, -0.4973092 ,
> 0.7457228 ,
>             -0.73969131, -0.67288704, -0.00893311])
> 
> In [4]: a.resize((9,))
> ---------------------------------------------------------------------------
> <type 'exceptions.ValueError'>            Traceback (most recent call
> last)

You'll notice that this doesn't happen when you run those commands as
a script.  IPython remembers the answer to the last command (as '_'
and in the output history), hence the reference that Numeric complains
about.

> Unfortunately, when applying resize on the actual array I have, I get a
> similar, yet slightly different error:
> 
> Traceback (most recent call last):
>   File "sym_get.py", line 37, in <module>
>     s.inquire_relation()
>   File "/usr/lib/python2.5/site-packages/mc_saxs/mc_rigid.py", line 915,
> in inquire_relation
>     print rotation, rotation.resize((9,))
> ValueError: resize only works on contiguous arrays
> 
> The arrays 'a' and 'rotation' are identical.

They may have identical values without having identical layout in
memory.  Try a.ascontiguousarray().

Cheers
Stéfan


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