[Numpy-discussion] bug in numpy.ndarray?

[Paul Anton Letnes]

On 8. mai 2011, at 17.32, Warren Weckesser wrote:

> 
> 
> On Sun, May 8, 2011 at 7:23 PM, Charles R Harris <charlesr.harris at gmail.com> wrote:
> 
> 
> On Sun, May 8, 2011 at 3:15 PM, Paul Anton Letnes <paul.anton.letnes at gmail.com> wrote:
> Hi,
> 
> it seems that I have found a bug in numpy.ndarray. numpy 1.5.1, python 2.7.1 from macports on mac os x 10.6.7. I got the same error on Fedora 14 with numpy 1.4.1 and python 2.7. Appending a [0] to the last line solves the problem.
> 
> % python testcrash.py                                                                                                                                          [14:13:27 on 11-05-08]
> <type 'numpy.ndarray'> [ 12.+0.1j]
> <type 'numpy.ndarray'> [ 1.+0.1j]
> complex128
> Traceback (most recent call last):
>  File "testcrash.py", line 11, in <module>
>    A[0] = A[0] + (eps1 - eps2)
> TypeError: can't convert complex to float
> 
>  % cat testcrash.py
> #!/usr/bin/env python
> 
> import numpy
> 
> A = numpy.zeros(10, dtype=numpy.complex128)
> eps1 = numpy.complex128([12.0 + 0.1j])
> eps2 = numpy.complex128([1.0 + 0.1j])
> 
> It's the brackets, numpy.complex128([1.0 + 0.1j]) is a 1d array, not a scalar. The error message is less than helpful though.
> 
> 
> 
> But the same pattern works fine with float64:
> 
> In [2]: x = array([1.0, 2.0])
> 
> In [3]: y = array([10.0])
> 
> In [4]: x[0] = y   # Works
> 
> In [5]: a = array([1.0, 2.0], dtype=complex128)
> 
> In [6]: b = array([10.0 + 1j])
> 
> In [7]: a[0] = b   # Error
> ---------------------------------------------------------------------------
> TypeError                                 Traceback (most recent call last)
> 
> /Users/warren/<ipython console> in <module>()
> 
> TypeError: can't convert complex to float
> 
> 
> Something is fishy about that.
> 
I agree. One thing is if arrays don't support this kind of assignment, but behavior should be the same for complex and float. IMHO.

Paul