[Numpy-discussion] numpy.array(arr.flat) mutates arr if arr.flags.fortran: bug?

Zachary Pincus zachary.pincus@yale....
Wed Mar 24 14:13:04 CDT 2010


Hello,

I assume it is a bug that calling numpy.array() on a flatiter of a  
fortran-strided array that owns its own data causes that array to be  
rearranged somehow?

Not sure what happens with a fancier-strided array that also owns its  
own data (because I'm not sure how to create one of those in python).

This is from the latest svn version (2.0.0.dev8302) but was also  
present in a previous version too.

Zach


In [9]: a = numpy.array([[1,2],[3,4]]).copy('F')

In [10]: a
Out[10]:
array([[1, 2],
        [3, 4]])

In [11]: list(a.flat)
Out[11]: [1, 2, 3, 4]

In [12]: a # no problem
Out[12]:
array([[1, 2],
        [3, 4]])

In [13]: numpy.array(a.flat)
Out[13]: array([1, 2, 3, 4])

In [14]: a # this ain't right!
Out[14]:
array([[1, 3],
        [2, 4]])

In [15]: a = numpy.array([[1,2],[3,4]]).copy('C')

In [16]: numpy.array(a.flat)
Out[16]: array([1, 2, 3, 4])

In [17]: a
Out[17]:
array([[1, 2],
        [3, 4]])



More information about the NumPy-Discussion mailing list