numpy-discussion

[Numpy-discussion] take behaviour has changed

[Christian K. <ck...@ho...>]

Hi,
from 1.0b1 to 1.0rc1 the default behaviour of take seems to have changed when
omitting the axis argument:

In [13]: a = reshape(arange(12),(3,4))

In [14]: take(a,[2,3])
Out[14]: array([2, 3])

In [15]: take(a,[2,3],1)
Out[15]:
array([[ 2,  3],
       [ 6,  7],
       [10, 11]])

Is this intended?

Christian

Re: [Numpy-discussion] take behaviour has changed

[Bill B. <wb...@gm...>]

Yep, check the release notes:
http://www.scipy.org/ReleaseNotes/NumPy_1.0
search for 'take' on that page to find out what others have changed as well.
--bb

On 9/22/06, Christian Kristukat <ck...@ho...> wrote:
> Hi,
> from 1.0b1 to 1.0rc1 the default behaviour of take seems to have changed when
> omitting the axis argument:
>
> In [13]: a = reshape(arange(12),(3,4))
>
> In [14]: take(a,[2,3])
> Out[14]: array([2, 3])
>
> In [15]: take(a,[2,3],1)
> Out[15]:
> array([[ 2,  3],
>        [ 6,  7],
>        [10, 11]])
>
> Is this intended?
>
> Christian
>
>
>
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Re: [Numpy-discussion] take behaviour has changed

[Christian K. <ck...@ho...>]

Bill Baxter <wbaxter <at> gmail.com> writes:

> 
> Yep, check the release notes:
> http://www.scipy.org/ReleaseNotes/NumPy_1.0
> search for 'take' on that page to find out what others have changed as well.
> --bb

Ok. Does axis=None then mean, that take(a, ind) operates on the flattened array?
This it at least what it seem to be. I noticed that the ufunc behaves
differently. a.take(ind) and a.take(ind, axis=0) behave the same, so the default
argument to axis is 0 rather than None.

Christian

Re: [Numpy-discussion] take behaviour has changed

[Travis O. <oli...@ie...>]

Christian Kristukat wrote:
> Bill Baxter <wbaxter <at> gmail.com> writes:
>
>   
>> Yep, check the release notes:
>> http://www.scipy.org/ReleaseNotes/NumPy_1.0
>> search for 'take' on that page to find out what others have changed as well.
>> --bb
>>     
>
> Ok. Does axis=None then mean, that take(a, ind) operates on the flattened array?
> This it at least what it seem to be. I noticed that the ufunc behaves
> differently. a.take(ind) and a.take(ind, axis=0) behave the same, so the default
> argument to axis is 0 rather than None.
>   

What do you mean.  There is no "ufunc" take.  There is a function take 
that just calls the method.  The default arguments for all functions 
that match methods are the same as the methods (which means axis=None).  
However, in oldnumeric (which pylab imports by the way),  the default 
axes are the same as they were in Numeric. 

Also, if you have a 1-d array, then the axis argument doesn't make any 
difference.   Please clarify what you are saying to be sure we don't 
have a bug floating around.



-Travis

Re: [Numpy-discussion] take behaviour has changed

[Christian K. <ck...@ho...>]

Travis Oliphant <oliphant.travis <at> ieee.org> writes:

> 
> Christian Kristukat wrote:
> > Bill Baxter <wbaxter <at> gmail.com> writes:
> >
> >   
> >> Yep, check the release notes:
> >> http://www.scipy.org/ReleaseNotes/NumPy_1.0
> >> search for 'take' on that page to find out what others have changed as well.
> >> --bb
> >>     
> >
> > Ok. Does axis=None then mean, that take(a, ind) operates on the
> > flattened array?
> > This it at least what it seem to be. I noticed that the ufunc behaves
> > differently. a.take(ind) and a.take(ind, axis=0) behave the same, so
> > the default
> > argument to axis is 0 rather than None.
> >   
> 
> What do you mean.  There is no "ufunc" take.  There is a function take 
> that just calls the method.  The default arguments for all functions 

Sorry, I never really read about what are ufuncs. I thought those are class
methods of the ndarray objects... Anyway, I was refering to the following
difference:

In [7]: a
Out[7]:
array([[ 0,  1,  2,  3,  4,  5],
       [ 6,  7,  8,  9, 10, 11]])

In [8]: a.take([0])
Out[8]: array([[0, 1, 2, 3, 4, 5]])

In [9]: take(a,[0])
Out[9]: array([0])

To be sure I understood: Does axis=None then mean, that take operates on the
flattened array?

Christian

Re: [Numpy-discussion] take behaviour has changed

[Travis O. <oli...@ie...>]

Christian Kristukat wrote:
>>> Ok. Does axis=None then mean, that take(a, ind) operates on the
>>> flattened array?
>>>       
Yes, that is correct.

> Sorry, I never really read about what are ufuncs. I thought those are class
> methods of the ndarray objects... Anyway, I was refering to the following
> difference:
>   
> In [7]: a
> Out[7]:
> array([[ 0,  1,  2,  3,  4,  5],
>        [ 6,  7,  8,  9, 10, 11]])
>
> In [8]: a.take([0])
> Out[8]: array([[0, 1, 2, 3, 4, 5]])
>
> In [9]: take(a,[0])
> Out[9]: array([0])
>   
Doh!.   That is a bug.  take(a,[0]) is correct a.take([0]) is not correct.

-Travis