[Numpy-discussion] Inplace reshape

Charles R Harris charlesr.harris@gmail....
Mon Apr 23 13:04:02 CDT 2007


On 4/23/07, Keith Goodman <kwgoodman@gmail.com> wrote:
>
> On 4/23/07, Christopher Barker <Chris.Barker@noaa.gov> wrote:
> > reshape(...)
> >      a.reshape(d1, d2, ..., dn, order='c')
> >
> >      Return a new array from this one.  The new array must have the same
> >
> >      number of elements as self.  Also always returns a view or raises a
> >      ValueError if that is impossible.;
>
> Here's a better doc string that explains "This will be a new view
> object if possible; otherwise, it will return a copy."
>
> >> numpy.reshape?
> Type:           function
> Base Class:     <type 'function'>
> String Form:    <function reshape at 0xb78894c4>
> Namespace:      Interactive
> File:
> /usr/local/lib/python2.4/site-packages/numpy/core/fromnumeric.py
> Definition:     numpy.reshape(a, newshape, order='C')
> Docstring:
>     Return an array that uses the data of the given array, but with a new
>     shape.
>
>     :Parameters:
>       - `a` : array
>       - `newshape` : shape tuple or int
>         The new shape should be compatible with the original shape. If an
>         integer, then the result will be a 1D array of that length.
>       - `order` : 'C' or 'FORTRAN', optional (default='C')
>         Whether the array data should be viewed as in C (row-major) order
> or
>         FORTRAN (column-major) order.
>
>     :Returns:
>       - `reshaped_array` : array
>         This will be a new view object if possible; otherwise, it will
> return
>         a copy.
>
>     :See also:
>       numpy.ndarray.reshape() is the equivalent method.



I think that it should raise an error, or warn, if it needs to make a copy,
but that isn't the  tradition. Reshape does raise an error if the product of
the dimensions isn't the same for both the original and the reshaped array.

Chuck
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