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Polynomial can't be evaluated on list of numbers only ndarray of numbers #17949

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jjmortensen opened this issue Dec 7, 2020 · 4 comments · Fixed by #24349
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Polynomial can't be evaluated on list of numbers only ndarray of numbers #17949

jjmortensen opened this issue Dec 7, 2020 · 4 comments · Fixed by #24349
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component: numpy.polynomial

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@jjmortensen
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Is it on purpose that this doesn't work:

>>> np.polynomial.Polynomial([1, 2])([3, 4])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/jensj/.local/lib/python3.7/site-packages/numpy/polynomial/_polybase.py", line 482, in __call__
    arg = off + scl*arg
TypeError: can't multiply sequence by non-int of type 'numpy.float64'

but this does:

>>> np.polynomial.Polynomial([1, 2])(np.array([3, 4]))
array([7., 9.])
@rossbar
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rossbar commented Dec 7, 2020

My feeling is that __call__ should support array-likes, so this should be fixed.

@IngErnestoAlvarez
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It would be sufficient if it casts an array-like parameter to np.array inside the __call__ function?

This was referenced Mar 17, 2021
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WarrenWeckesser added a commit to WarrenWeckesser/numpy that referenced this issue Aug 6, 2023
@WarrenWeckesser
BUG: polynomial: Handle non-array inputs in polynomial class __call__…
df8b71a 
… method.

Use the utility function `polyutils.mapdomain()` in the `__call__` method of
`ABCPolyBase`.  This closes numpygh-17949 because `mapdomain` calls `np.asanyarray(x)`
on its first argument.

Closes numpygh-17949.
@WarrenWeckesser WarrenWeckesser mentioned this issue Aug 6, 2023
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@WarrenWeckesser
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I just ran into this. The issue still exists with the main development branch:

In [11]: np.__version__
Out[11]: '2.0.0.dev0+766.g8627dc962'

In [12]: p = np.polynomial.Polynomial([1, -2.5, 3, 1])

In [13]: p([2, 3, 4])
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[13], line 1
----> 1 p([2, 3, 4])

File ~/repos/git/forks/numpy/build-install/usr/lib/python3.11/site-packages/numpy/polynomial/_polybase.py:512, in ABCPolyBase.__call__(self, arg)
    510 def __call__(self, arg):
    511     off, scl = pu.mapparms(self.domain, self.window)
--> 512     arg = off + scl*arg
    513     return self._val(arg, self.coef)

TypeError: can't multiply sequence by non-int of type 'numpy.float64'

@charris
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charris commented Aug 6, 2023

Polynomials can be evaluated on objects, matrices for example, and a list is just another object, but fails because it cannot be multiplied by floats (coefficients).

rossbar pushed a commit that referenced this issue Aug 6, 2023
@WarrenWeckesser
BUG: polynomial: Handle non-array inputs in polynomial class __call__…
476a69d 
… method. (#24349)

Use the utility function `polyutils.mapdomain()` in the `__call__` method of
`ABCPolyBase`.  This closes gh-17949 because `mapdomain` calls `np.asanyarray(x)`
on its first argument.

Closes gh-17949.
@eendebakpt eendebakpt mentioned this issue Jul 4, 2024
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@charris @WarrenWeckesser @rossbar @jjmortensen @IngErnestoAlvarez