On Wed, Apr 27, 2016 at 8:49 PM, Alexander Griffing <argriffi@ncsu.edu> wrote:

On Wed, Apr 27, 2016 at 7:48 PM, Elliot Hallmark <Permafacture@gmail.com> wrote:
> Hello,
>
> I haven't worked hard yet to create a minimal runnable (reproduce-able)
> example but I wanted to check if this sounds familiar to anyone.
>
> I have a pretty involved program that resizes arrays in place with
> arr.resize. When I run it with python it completes and gives the expected
> result. When I run it in Ipython, I get the following error:
>
> ```
> ---> 43 self._buffer.resize((count,)+self._dim)
> 44
> 45
>
> ValueError: cannot resize an array that references or is referenced
> by another array in this way. Use the resize function
> ```
>
> It was consistently doing this on the same array, after resizing two others
> before hand, even after rebooting. But trying to track it down it goes away
> even if I undo everything I did to try and track it down.

You might find the %xdel magic to be useful:

In [1]: %xdel?

Docstring:

Delete a variable, trying to clear it from anywhere that

IPython's machinery has references to it. By default, this uses

the identity of the named object in the user namespace to remove

references held under other names. The object is also removed

from the output history.

Options

-n : Delete the specified name from all namespaces, without

checking their identity.

>
> Does this sound familiar?
>

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>

I'd guess the issue is that your environment (IPython or IDLE or
whatever) is keeping a reference to your array, for example so that
you can refer to earlier outputs using the underscore _. Here's how I
was able to reproduce the problem:

This is OK:

>>> import numpy as np
>>> a = np.arange(10)
>>> a.resize(3)
>>> a
array([0, 1, 2])

This gives an error:

>>> import numpy as np
>>> a = np.arange(10)
>>> a
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> a.resize(3)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: cannot resize an array that references or is referenced
by another array in this way. Use the resize function

Cheers,
Alex
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