I need a numpy array with 3-rows and 1 Column (for pyCGNS when creating a Zone).
And This Must be true when asking if it is NPY.isfortran(X).
I tried several ways, but none worked.
e.g.
a1 = NPY.zeros((3,1),order='F')
print NPY.isfortran(a1)
->False
The function is obsolete. it returns:
True if the array is Fortran contiguous BUT not C contiguous.
In [421]: np.isfortran(a1)
Out[421]: False
In [422]: a1.flags
Out[422]:
C_CONTIGUOUS : True
F_CONTIGUOUS : True
OWNDATA : True
WRITEABLE : True
ALIGNED : True
UPDATEIFCOPY : False
Your array is fortran contiguous AND C contiguous.
Quoting the isfortran documentation (emphasis mine):
Returns True if the array is Fortran contiguous but not C contiguous.
This function is obsolete and, because of changes due to relaxed stride checking, its return value for the same array may differ for versions of NumPy >= 1.10.0 and previous versions. If you only want to check if an array is Fortran contiguous use
a.flags.f_contiguousinstead.
There are a few things to note here:
There is an alternative way to check the array, that should work for your case:
a = np.zeros((3, 1), order='F')
print(a.flags)
# C_CONTIGUOUS : True
# F_CONTIGUOUS : True
# OWNDATA : True
# WRITEABLE : True
# ALIGNED : True
# UPDATEIFCOPY : False
print(a.flags.f_contiguous)
# True
You cannot edit flags. However, there are a few tricks. For example, you can use transpose to turn a 2D C array into an F array (albeit with swapped dimensions):
print(np.ones((3, 2), order='C').flags)
# C_CONTIGUOUS : True
# F_CONTIGUOUS : False
# ....
print(np.ones((3, 2), order='C').T.flags)
# C_CONTIGUOUS : False
# F_CONTIGUOUS : True
# ....
pyCGNS can not create a column vector.
I solved the problem by programming the CGNS header (base and zone) in C.
And then loaded the created file from the C program in pyCGNS and built upon it.
