[Numpy-discussion] Problem using polyutils.mapdomain with fromfunction

Charles R Harris charlesr.harris@gmail....
Sun Jul 25 09:08:25 CDT 2010


On Sun, Jul 25, 2010 at 2:32 AM, David Goldsmith <d.l.goldsmith@gmail.com>wrote:

> Why am I being told my coefficient array is not 1-d when both coefficient
> arrays--old and new--are reported to have shape (2L,):
>
> C:\Users\Fermat>python
> Python 2.6.5 (r265:79096, Mar 19 2010, 18:02:59) [MSC v.1500 64 bit
> (AMD64)] on
> win32
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import numpy as np
> >>> np.version.version
> '1.4.1'
> >>> from numpy.polynomial import polyutils as pu
> >>> nx = 1
> >>> ny = 1
> >>> def whydoesntthiswork(x, y):
> ...     old = np.array((0,2)); print old.shape
> ...     new = np.array((-1,1)); print new.shape
> ...     X = pu.mapdomain(x, old, new)
> ...     return X
> ...
> >>> result = np.fromfunction(whydoesntthiswork, (nx, ny))
> (2L,)
> (2L,)
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "C:\Python26\lib\site-packages\numpy\core\numeric.py", line 1539, in
> from
> function
>     return function(*args,**kwargs)
>   File "<stdin>", line 4, in whydoesntthiswork
>   File "C:\Python26\lib\site-packages\numpy\polynomial\polyutils.py", line
> 280,
> in mapdomain
>     [x] = as_series([x], trim=False)
>   File "C:\Python26\lib\site-packages\numpy\polynomial\polyutils.py", line
> 139,
> in as_series
>     raise ValueError("Coefficient array is not 1-d")
> ValueError: Coefficient array is not 1-d
>
> Thanks in advance,
>
>
Because fromfunction passes 2d arrays to  whydoesntthiswork and mapdomain
doesn't accept 2d arrays as the first argument. That looks like an
unnecessary restriction, open a ticket and I'll fix it up.

Chuck
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